Small objects like spiral univalve shells

Thomas BlandNote on certain Insect Larva-Sacs, described as Species of Valvatae, New York, The Annals of the Lyceum of Natural History, vol. VIII, mai 1865, pp. 144-149.

Some years ago I collected in the Island of Jamaica, W. I.,  from a stream of fresh water, small objects like spiral univalve shells, which I supposed to be mollusks, but after examination and inquiry discovered my error.

Subsequently I learned that an object of similar character had been described by Mr. Isaac Lea as Valvata arenifera, which proved, however to be the case of the larva of a Phryganidous insect. At a later period specimens, not unlike those noticed in Jamaica, were sent to me from Canada West, under the name of Thelidomus Braziliensis Swainson.

De Kay (Nat. Hist. of New York, Mollusca, p. 119), with his description of Valvata sincera Say, has the following observation :-

« There is frequently found associated with this and the preceding species (V. unicarinata) an agglutinated arenaceous mass, resembling them very much in form. This has been described as V. arenifera in the Transactions of the American Philosophical Society (vol. 4 p ; 104, pl. 15, fig. 36. A.B), and has since ben erected by Mr. Swainson into the new genus Thelidomus (see Lardner’s Cabinet Cyclopoedia, N° 123, pp. 226, 353). It is believed to be case of the larva of some aquatic insect, possibly a Phryganea . »

In the summer of 1862, I received from Mr. Henry Rousseau a number of these larva-cases, collected by him in the vicinity of Troy, N.Y. The specimens were in alcohol, but at my request Mr. Rousseau sent to me living ones, which I placed in a small aquarium, wishing autumn and winter the larvae were extremely active, creeping about on the stones and feeling apparently on confervae. If disturbed, the larva withdrew into its abode, which then seemed to be somewhat firmly fastened or secured to the object on which the case happened to rest.

Early in the spring of 1863, I noticed what appeared to be the exuviae of the nympha of an insect floating on the surface of the water in the aquarium, and empty larva cases at the bottom. Suspecting that some of the insects had flown, I placed a gauze net over the aquarium, and in  a few days obtained several perfect imagines. Believing that these would be very interesting to naturalists, I consulted Mr Akhurst, and at his suggestion forwarded the insects and cases to Mr. P. R. Uhler, who reported that they probably belonged to the genus Helicopsyche of the family Hydropsychidae, and that the species was perhaps new. He  sent the specimens to Europe for determination by Dr. Hagen, but I have not a present heard the result.

In a paper entitled «  Descriptions of New Species of Fluviatile and Terrestrial Operculate Mollusca from Trinidad » (Ann. and Mag. Of Nat. Hist., N° 82, Oct., 1864) by Mr. R.J. Lechmere Guppy, is the following description evidently of a Helicopsyche-sac, but treated by the author as a Valvata.

« Valvata agglutinans.- Shell trochiform-depressed, perforate, entirely comoposed of numerous minute grains of mineral matter ; whorls 3-4, almost carinate, flatttened beneath ; umbilicus circular ; aperture very oblique, circular, the margins shortly united on the penultimate whorl ; peristome simple, irregular. Height 0,1 inch, greatest breadth 0.17 inch. « It lives on the surface of rocks and stones in the hill streams of the northern part of Trinidad. »

Tryon (Amer. Journ. Of Conchology, Part I., February, 1865) justly remarks : – «  This fresh description of Phryganiae as Valvatae is amusing ; naturalits seem resolved to consider them Mollusca ! »

As these Helicopsyche-sacs have from time attracted much attention, and their true character has been misapprehended, I add a copy of an interesting note on the subject from Von Siebold’s work On a true Parthenogenesis in Moths ans Bees (English translation by W. S. Dallas, pp. 28-30. London, 1857).

« Besides Psyche Helix, there are some other insects whose larvae as case-bearers, manufacture sacs in the form of a snail-shell. In the genus Psyche itself there occurs another species the caterpillars of which, like those of Psyche Helix, bear about with them a spirally-twisted sac. By the kindness of Herr Zeller of Glogau, and Dr. Rosenhauner of Erlangen, I possess two earth-colored, snail-like sacs, with perfectly flat convolutions (Figs. 15-17), found in Sicily and Spain. They are nearly three times as large as the sacs of Psyche Helix, and from their different form and size belong to another species, to which I will give the provisional name of Psyche Planorbis. Both sacs, like those of Psyche Helix, are covered with fine grains of earth and sand cemented on them. Behind the uppermost and narrowest half-turn there is also a lateral aperture, which is due to an interruption in the walls of the sac taking place here (Fig. 15 a).

« In the family of the Phryganidae, also, larvae occur, which form a spirally-twisted domicile. Th first notice of this war furnished by Shuttleworth (in the Mitheilungen der naturforschenden Gessellschaft in Bern, June, 1843, p. 20), and as this is but little known, I will reproduce it here literally. The passage in question runs as follows : « Amongst the mollusca collected by Blanner in Corsica, there was a considerable number of a shell, which was at first taken for an undescribed species of Vavata arebifera of Lea (Obser. p. 114, tab. 15, Figs. 36, a and b), from North America. The perfectly regular, spirally convoluted shell consists of a very fine transparent membrane, upon which very small grains of sand and stones are fixed with the greatest regularity. The circular orifice is closed by a very delicate,  apparently spirally convoluted membranous operculum. The general form, as well as the dimensions, remind one strikingly of the Valvata depressa Pfr. In all the individuals provided with anoperculum, there was either the larva or the nympha of an insect, probably belonging to the genus Phryganea, which, bent into a half-spiral, lay singly in each shell. Under the microscope the opercula exhibited, besides the spiral or regularly concentric structure above referred to, an excentric longitudinal opening, running parallel to the inner margin. Specimens of the Valvata arenifera of Lea, which I have recently obtained from Vienna, exhibit precisely the same structure both of the shell and operculum. In Réaumur’s Mémoires pour servir à l’Histoire des Insectes, tom. III, p. 193, pl. 15, Figs. 22-24, there is a short description and figure of a (spirally convoluted) Phryganea-case (occuring in Switzeland). This species of Réaumur ‘s however, differs in every other particular from the species above described, and also appears to possess no operclum

« The case last referred to by Shuttleworth belongs to Psyche Helix ; the other one, which resembles a Valvata, on the contrary, is a very different thing (see my figures 18-22), and is certainly produced by a Phryganidous insect. I saw several of the habitations of this insect in Bremi’s collection at Zurich, partly collected in Corsica and partly on the Lake of Como. Bremi  has given the name of Helicopsyche Schuttleworthi to the questionnable Phryganidan from which these spiral cases are derived ; and many specimens of a similar smaller case have been since sent to him from a brook in Porto Rico, the inhabitant of which Bremi has named Helicopsyche minima. By the kindness of Herr Bremi I have obtained several specimens of both kinds, which are essentially different in their structure from the sacs of Psyche Helix. As regard their size, the diameter of the largest sacs of Helicopsyche Schuttleworthi is 2 lines (Rhenish), and of those of H. minima 1 line. A principal distinction between these Phryganidan domiciles and the spiral sacs of Psyche consists in the fact, that whilst in the case of Psyche Helix extremely fine grains of sand are stuck as a coating upon the outer surface of the white web of the sac-walls, in Helicopsyche the walls of the habitation are formed directly and solely of larger, polygonal particles of sand, closely cemented together from within and without. The caterpillars of Psyche also never close their sacs with an operculum. But that the Helicopsyche-sacs are really produced by a Phryganidous insect, I ascertained from the content which I extracted from two cases of Helicopsyche minima still furnished with opercula. Those consisted of a dried pupa, which in the form of the legs and of the long antennae, the four hairy rudiments of wings, and the two biting jaws, exactly resembled a Phryganidae. The description given by Lea of his Valvata arenifera ( in his Observations onNajades and Descriptions of New Species, vid. Trans. Of the Amer. Phil. Soc. Vol IV, Philadelphia, 1834, p. 104, pl. 15, Fig. 36 a, b. See my copies,Figs. 23, 24) runs as follows : « Tesata orbiculata, convexa ; anfractibus tribus, qui arenis agglutinatis operiuntur ; umbilico lato ; spira obtusa. » Hab. – Cumberland River, near Nashville. Length four-twentiechs of an inch. Remarks. – This very curious and interesting species was among the freshwater shells so disinterestedly sent to me by the Lyceum of Natural History of New York to be examined and inserted in this paper. It has the singular property of strengthening its whorls by the agglutination of particles of sand &c., by which it is entirely covered, and in this charater it resembles Trochus agglutinans Lam (T. conchyliophorus, Authors). The spex, in all specimens which I have had an opportunity of examining, is broken. The operculum was observed in two specimens sufficiently perfect to exhibit a striated horny structure ».

« The sacs of Helicopsyche minima communicated to me by Bremi, agree almost perfectly with this shell of Valvata arenifera described and figured by Lea. Even the bronze-green coloris common to both of them. The presence of an operculum is also in favor of the derivation of this habitation from a Phryganidous insect, as the sac-bearers amongst the Lepidoptera from no operculum, but always spin down their sac by its lower aperture to foreign substances. Moreover, the opercula, of which I found several in my specimens of the sac of Helicopsyche minima, had also a striated appearance, like those of Valvata arenifera. They were smaller than the aperture of the sac, and consequently only close dit imperfectly. On examining them with the microscope, I detected a fibrous structure in the these opercula, arising from comparatively coarse-spun threads, sticking close together ; at the margins of these opercula single threads protrude, by which they were ubited with the mouth of the sac. In my specimens of the sacs of Helicopsyche Schuttleworthi I perceived no opercula ; they had probably fallen off, or perhaps were not formed when these sacs were collected. »

Von Siebold gives figures (referred to in the note above quoted) of the caterpillar-sacs of Psyche Helix and Psyche Planorbis, of the sac of Helicopsyche Schuttleworthi and of Valvata arenifera, enlarged and copied from Lea. To the « Explanation of the figures » Von Siebold adds the following supplementary observation :-

«  At my last visit to Zurich I saw in Bremi’s collection the cases of a third larger species of Helicopsyche, which Bremi obtained from Shuttleworth, and has named Helicopsyche Colombiensis. These case come from Puerto-Caballo ; they have a transverse diameter of 1 8/10 lin., and a height of 1 2/ 10 lin.. Rhenish, and are manufactured out of comparatively very coarse, rusty-brown stones. With regard to Helicopsyche Schuttleworthi, Bremi informed me, that the cases of this Phryganidous insect have now been found also on the Lake of Geneva. »

The cases received from Mr Rousseau and from Canada are in size, form and construction somewhat similar to those figured by Von Siebold as Helicopsyche Shuttleworthi. In the operculum of the Troy specimens there is the longitudinal opening described by Shuttleworth.