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are poor, but the specimens -were from Bengal, and they present
no essential difference from immature shells of cornucopia, so Mr. Benson is doubtless correct. Reeve in Conch. Icon. quotes N. melanostoma as a synonym of N. crepidularia and ignores N. cornucopia altogether. Von Martens (Malakoz. Blatter, 1863, X, 127.) shews that the colour of the columella and lip is sometimes white and sometimes black in several Neritina of the Dnstia section.
The fact very probably is, that we have in this case an example of a phenomenon not uncommon in the animal kingdom. Two distinct races spring up side by side, arising from one type, and in the original locality do not change their form, but although they breed truly, they are only distinguishable by some slight constant distinction. As both, however, migrate into distant regions, the difference becomes greater, and at length both become so diverse, that no question can remain as to their being in common natural history talk, "distinct species." Thus while Ncritina cornucopia and N. depressa, inhabiting the Ganges delta, are scarcely distinguishable from each other by any more important character than the colour of the aperture, the same shells in Pegu have varied so much, that each differs from the other at least as mnch as it does from their congener N. crepidularia. In other places the race representing N. cornucopia may be perfectly undistinguishable from N. crepidularia, as appears- to have been observed by v. Martens in Singapore. It is highly probable that the origin of species through variation takes place in space as well as in time. More observations on this question are desirable.
Figures of the three forms occurring in the Pegu delta are added. Family PALUDINID^E? No. 21, Larina P Burmana, n. sp. PI. II, fig. 1.
Testa ovalo-globosa, imperforata, tenuis, castanea, striatula, nitidula. Spira conoidea, apice erosula, sutura valde impressa. Anfr. 5, rotundati, sensim descendenles, ultimus lumidus, subtus rotundatus. Apertura vix obliqua, subelliptica, superne angulata; peristoma rectum, lenue, marginibus callo tenui junctis, columellari cxpansd. f Operc. corneum. Long. 11, diam. 8 mill. Apertura 1\ mill[ longa, 6 lata.
Shell ovately globose, imperforate, thin, translucent, smooth, brownish, horny. Spire conoidal, apex eroded, suture deep. Whorls 5 (perhaps more in adult specimens), rounded, obsoletcly striated, rcgularly descending, the last tumid, ronnded beneath. Aperture nearly vertical, subelliptical, angulatc above. Peristome thin, straight, margins united by thin callus, columellar margin narrowly expanded.
The operculum of this peculiar species was unfortunately lost, and the animal was not observed. In the hurry of travelling, the specimens were placed in a box and forgotten, until the fleshy portions were too much decayed for examination. About half a dozen individuals were found under stones in the Myittaya creek, in the same place which yielded Iravadla ornata and other forms.
Mr. A. Adams, who very kindly aided me in determining some of tho species contained in my Pegu collections, suggested that this shell might possibly be a second species of the genus Larina, established by him for an Australian shell, the animal of which also is unknown. In appearance this shell somewhat resembles a Lymnea. It is not impossible that it may have affinities with Amphibola. I have a distinct impression that the shells possessed a horny operculum, or I should have been disposed to class them in the Velutinidce.
Testa depresso-conica, rotundato-ovalis, tennis, cpidermide ficscoolivaced indula, lineis radiantibus, striisqne confertis minutis conceiiiricis dectissata, intus caruleo albida, interdum fascia concentricd larted, vel eliam omnino hoc colore versus maryinem salurata, ad apicem ferruginca. Apex subcentralis, erosa.
Major diam. 21J min. 20 alt. 6
Shell much depressed, conical, subcircularly oval, thin, covered with a very dark olive epidermis, always eroded at the apex, marked with fine radiating raised lines and with close and minute concentric striai of growth; inside the shell is bluish white, sometimes with one or more milky concentric bands, or the whole interior is milky, except the apex which is invariably ferruginous, the area so coloured having some correspondence to tho amount of external erosion, and the colour being evidently due to a deposition of shell insido to protect the animal as the external portion is corroded away.
This species is found on rocks, rarely on trunks of trees, in many of the creeks near high water mark, in brackish water. It was not met with near the sea, where the water was very salt.
The foot is large, filling the cavity of the shell, muzzle broad, tentacles long and fine, mouth not notched beneath. It .does not appear to keep to one place and form a hole for itself like some Patella, but it is very sluggish in its movements.
Not common. In Bombay this species abounds upon mud Hats. The animal is red.
Sub-class Pulmonifeea. Family AUEICULID^!. No. 24, Auricula Judge, L.
Thisspecies is completely blind, as has been noticed by von Martens (I'eber die Landschnecken der Molukken, Mulakoz. Blatter; 1803, X. 126) and as is shewn in Eydoux's drawing copied in Mrs. Gray's molluscs. The same is the case with all other species of the same group which I have examined. In some instances, e. g. the Bombay species, which has received, I believe, a MS. name from Mr. Benson, the eyes may be detected beneath the skin by looking very carefully. (Von Martens observed this in one instance in A. Judcd?) Such eyes can, however, be of but little use as percipient points to the animals. There is, however, one group of true Auricula?, typified by A. tulmla, Quoy and Gaimard, in which the eyes are normally developed, the same as in Melampus, Cassidula, and other Auriculidm. A small species of this type inhabits Bombay. The forms belonging to this sub-division appear also distinguished by a more elevated spire. Further observations are, however, necessary before a division of the genus can be proposed on these grounds, as there appears great probability that the two forms pass into each other.
I iound specimens of A. Jwla alive under the bark of dead trees, on muddy banks of creeks, in places overflowed by the tide. Unquestionably, so far as my experience goes, none of the Eastern Auriculida (Auricula, Cassidula, Melampus, Pythia, Phcolrcmu) are land shells, all arc met with in places overflowed by salt or brackish water at every tide. They are in fact true estuary shells.
Some of the specimens of this species collected by me shew an almost complete passage into A. dactylus Pfeiffer, as described and figured in Novitates Conchologica I, 15, pi. V. fig. 15. 16. This species is stated by Mr- Theobald to be found at Mergui (J. A. S. B. for 1857, xxvi. 253.)
No. 25, Auricula nitidula, n. sp. PI. II. fig. 5, 6.
Testa non rimata, subfusiformi oblonga, solida, nitidula, suj epidermide olivaced alba, lineis impressis confertis verticalibus minutissime rugata, aliis spiralibus granulato-decussata, sculpturd infra suluram magis impressd. Spira conoidea, apice eroso, sutura impressa. Anfr. 5 convexi, ultimus vix descendens, $ longitudinis subcequans, basi rotundatus. Apertura verticalis, plicts parietales 2, supera parva, profunda, alia obliqua, plica columcllaris haud valida, diagonalis : perist. crassum, marginibus callo tenui junctis, dextro superne vix sinuato, intus callo elevato incrassato.
Long. 28, diam. 12J mill. Apertura c. perist. 19 mill. longa, inlus 5 lata.
Shell not rimate, subfusiformly oblong, solid, smooth, having a greasy lustre, whito, epidermis olive, covered with minute granulations produced by the intersection of vertical and spiral impressed lines, both very close and the former sinuous, the sculpture being most strongly marked below the suture. Spire conoidal, apex eroded, suturo impressed. Whorls 5 convex, the last nearly § of the whole length, scarcely descending,'rounded at the base. Aperture vertical with 2 parietal plicae, the upper one small, far inside; the lower strong, oblique; columellar plica moderate in size, diagonal; the peristome thick, the margins united by a thin callus which is somewhat expanded upon the penultimate whorl, the right margin scarcely sinuate above, and thickened inside.
This species which is found very rarely with the last, exactly resembles it in general form, but has rounded whorls and finer sculpture, besides being of much smaller size. The animal is white, while that of A, Judos is mottled. A. nitidula somewhat resembles A. Chinensis Pfr. which, however, is much less attenuate below, and differs in the form of the aperture, &c.
But two or three specimens of this form were met with. In Mr. Theobald's lists of Burmese shells, A. gluns, Bens, is mentioned. I can find no description of this species, and cannot therefore say if it be the present form or not.
No. 26, Flecotrema Cumingiana, n. sp. PI. II. fig. 16.
Testa subrimata, subelliptico-ovata, solida, punctis impressis crebris, Hneas spirales confertas ftsrmantibus, striisque incrementi obliquis ornata, ftrrugineo-fusca. Spira conoidea, lateribus vix convexinsculis, apice erosa, sutura lavi lineari. Anfr. 4 superst., superi planulati, vix discreti, sulci's spiralibus punctatis 4 notati, ultimus ad peripheriam subangnlalus, subtus compressinsculus. Apertura vix obliqua, plicis parietalibus 2, superiori brevi obliqua, altera intrante, extus bifida, plied ohmellari subobliqud; peristoma rectum, pone limbum acutum intus callosum, margine dextro tridentato.
Long. 5, diam. 3 mill. Apert. 3J mill. longa.
Shell subrimate, subelliptically ovate, solid, marked with close spiral lines, formed of thickly set punctiform impressions, and with oblique striae of growth ; reddish brown in colour. Spire conoidal, the sides barely convex, apex eroded, suture flat. Whorls 4 remaining, the npper flat, scarcely distinguishable, marked with 4 spiral dotted lines, the last whorl subangulate at the periphery, somewhat compressed below. Aperture very slightly oblique, with two parietal folds, the upper short, oblique, the lower re-entering, externally bifid, the columellar fold sub-oblique ; peristome straight, margin sharp, but inside the sharp edge thickened and bearing 3 teeth within the right margin.
This species was rather scarce, crawling on mud in company with Assiminea rubella. It is distinguished from its allies, P. striata, Philippi, and P. punctostriata, H. and A. Adams, by its low spire and minute sculpture. In naming it after the late Mr. Hugh Cuming, I adopt the only means in my power of acknowledging my obligations to that gentleman for the very liberal manner in which he allowed me access to his collections, for the purpose of comparing and identifying my Pegu shells.
Besides the above Auriculidce, I have received a Pythia which appears to be a variety of P. trigona, Troschel, from Mr. Theobald and Mr. Fedden, who both met with it on the Arakan coast, not far north of Cape Negrais. It is singular that I did not meet with species of either Cassidula or Mdampus, as I havo reason to believe that both inhabit the Irawadi delta or its immediate vicinity. Mr. Theobald has sent me Cassidula aurisfclis, Brug. from Arakan.