Part 45 (1/2)
(60) _Neritina porcata_ (Gould) _Hab._ St. Christoval, and Faro Island, Bougainville Straits, in streams.
(61) _Neritina variegata_ (Lesson) _Hab._ St. Christoval, Ugi; Simbo or Eddystone; Faro Island, Bougainville Straits; Choiseul Bay; in streams.
(62) _Neritina turtoni_ (Recluz) _Hab._ A stream in the Shortland Islands; streams in Guadalcanar; imbedded in a dark calcareous loam exposed in the banks of a large stream near to its mouth at Sulagina on the north coast of St. Christoval.
(63) _Neritina brevispina_ (Lamarck) _Hab._ Streams in Shortland, Treasury, and Ugi Islands. The specimens from Treasury Island were dest.i.tute of spines.
(64) _Neritina squarrosa_ (Recluz) _Hab._ Streams in Treasury Island.
(65) _Navicella sanguisuga_ (Reeve) _Hab._ Streams in Faro Island, Bougainville Straits.
(66) _Navicella suborbicularis_ (Sowerby) _Hab._ Guadalcanar, St.
Christoval, Ugi, Treasury and Faro Islands in Bougainville Straits.
(67) _Unio guppyi_ (nov. spec.) _Hab._ Streams in the Shortland Islands.
(68) _Cyrena_, spec. _Hab._ In the lower parts of streams and in mangrove swamps, Choiseul Bay. _Note._--This species is not referred to in the original paper.
_Descriptions of the new species and varieties_,[490] by Mr. E. Smith.
[490] The numbers refer to the plates in Mr. Smith's paper (Proc.
Zool. Soc., June 1885).
(2) _Helix_ (_Nanina_) _nitidissima._ (Plate x.x.xVI. figs. 1, 1 _b_.) Sh.e.l.l thin, transparent, very glossy, depressed, narrowly perforate, pale brownish horn-colour above, whitish towards the umbilicus, sculptured with very faint lines of growth. Whorls 4-5, slightly convex, impressed and marginate above at the suture; last whorl large, rounded at the periphery. Aperture obliquely lunate; peristome simple, thin, slightly thickened and reflexed partly over the perforation. Spire low, but very little raised above the last whorl, obtuse at the apex. Greatest diameter 14 millim., smallest 12; height 9.
(3) _Helix_ (_Nanina_) _solidiuscula._ (Plate x.x.xVI., figs. 2, 2 _b_.) Sh.e.l.l very narrowly perforate, depressed, somewhat solid, dark chestnut-brown and a little glossy above, more s.h.i.+ning and paler beneath, becoming almost white at the umbilical region; whorls 6, convex, separated by a deepish suture, and, with the exception of two or three at the apex which are smooth, sculptured with strong, close-set, arcuate, and oblique striae on the upper surface, crossed with a few more or less distinct spiral lines. Body-whorl rounded at the periphery, or sometimes with the faintest indication of an angle, convex, and only exhibiting fine lines of growth below.
Aperture obliquely semi-lunate; peristome simple, but, owing to the solidity of the sh.e.l.l, seeming slightly thickened, especially on the very oblique columellar margin, which is shortly reflexed above over the perforation. Spire depressed-conoid, having the least convex outlines and an obtuse apex. Greatest diameter 18 millim., smallest 16, height 12; aperture 8 long, 4 wide.
This species is well distinguished by its comparative solidity and strong sculpture on the upper surface.
(4) _Helix_ (_Corasia_) _tricolor_ (Pfeiffer). (Plate x.x.xVI., figs.
3, 3 _b_.) A specimen obtained on the north coast of the same island of St. Christoval, by Mr. Guppy, is worthy of special mention, and may be termed var. _picta_, on account of the undulating reddish-brown stripes which ornament both the upper and lower surfaces.
A similar example was also collected by Dr. A. Corrie and presented to the Museum. The markings on these two sh.e.l.ls are very striking and distinctly visible within the aperture.
(11) _Helix_ (_Geotrochus_) _guppyi._ (Plate x.x.xVI. fig. 4.) Sh.e.l.l elevately conical, thin, pale yellow, ornamented with conspicuous nearly black or black-brown spiral bands, one above and one below the sutures of the upper whorls, and three upon the last, one sutural, the second peripheral, and the third basal. Volutions 6, rather slowly enlarging, a little convex, sculptured with fine oblique striae of growth, not glossy. Three first whorls livid purplish, the last rather sharply angled at the middle, not descending in front, having the basal band broad around the almost concealed perforation, and obsolete within the aperture. The latter is oblique, somewhat narrowed and pouting in front, banded within with three almost black and two white bands, the central one of the former being squarely truncate at the end, only the lower corner of it touching the margin of the lip, which is pale oblique, receding, a little expanded and reflexed in front and at the columellar margin, the upper end of which is spread over and nearly conceals the small umbilicus. Height 22 millim., greatest diameter 19, smallest 16.
This species is remarkable for the striking contrast of its colour-bands and the angular character of the last whorl.
(12) _Helix_ (_Geotrochus_) _dampieri_, Angas, var. (Plate x.x.xVI.
fig. 5.) Sh.e.l.l imperforate, subglobose, conoid, light brown or fawn-colour, here and there minutely dotted with dark-grey specks, with a broad white band around the middle of the penultimate whorl and two upon the last, one above and the other below the middle, also a narrow white line revolving up the spire beneath the suture, and a dark brown zone surrounding the pale or yellowish umbilical region. Whorls 5, a little convex above, somewhat glossy, obliquely and very finely striated by the lines of growth, the last more or less concentrically striated beneath, shortly descending at the aperture which is white within. Lip a little thickened, edged with reddish brown, only slightly expanded on the right side, more dilated below, produced into a thin transparent callosity over the umbilical region, united above to the upper extremity of the peristome. Columellar margin oblique, white or partly tinged with reddish brown, thickened and terminating below within the edge of the lip. Height 19 millim., greatest diam. 22, smallest 19.
The specimens from the Solomon Islands are smaller than the type with which, through the kindness of Mr G. F. Angas, I have compared them. They also have the peristome brown, and the basal band is darker.
(14) _Helix_ (_Geotrochus_) _cleryi_, Recluz (Plate x.x.xVI. figs 6, 6 _b_). The specimens from Santa Anna (var. _meridionalis_ fig. 6 _b_) are smaller than the type, pale brown above, with a white thread-like line at the suture, and the acutely keeled periphery, paler beneath, especially towards the centre, and have the aperture particularly ac.u.minate at the termination of the keel.
The specimens from Simbo (var. _simboana_, fig. 6 _a_) are uniformly pale horn-colour, rather sharply carinate at the middle, and have the peristome white, considerably thickened and almost notched at the upper end of the columella, and the body-whorl is more contracted than in the typical form. The examples from Choiseul Bay, Shortland and Treasury Islands (var. _septentrionalis_, fig. 6) are all alike, of smaller dimensions than the normal form, thin pale brownish horn-colour, with rather more convex whorls than usual, the carina at the periphery being acute and thread-like as in the variety _simboana_.
Whether these several varieties should take specific rank is questionable, for, although there is considerable difference between the extreme forms even in the series of nearly one hundred specimens under examination, the gradual transition from one form to another is observable.
(16) _Helix_ (_Videna_) _sanctae annae._ (Plate x.x.xVI. figs. 7. 7 _b_.) Sh.e.l.l depressed-conoid, deeply umbilicated, very acutely keeled at the periphery, light brown, sometimes with a few radiating pale streaks on the upper surface, sculptured with oblique lines of growth. Whorls 5, rather slowly increasing, slightly convex, depressed and margined above the suture, last not descending, compressed above and below the keel, a little convex towards the umbilicus, which is moderately large. Aperture transverse, flesh-tinted within. Peristome simple, a little thickened along the basal margin, with the extremities united by a thin callus. Height 7 millim.; greatest diameter 17, smallest 15.