M. M. SCHEPMAN, LAND- AND FRESHWATER MOLLUSCA ETC. I S I 



This species seems to be allied to the preceding one, it is considerably smaller, more 

 depressed, without trace of spirals on the part subséquent to the pitted apex and remarkable 

 by the rufous spot. I should scarcely hâve described it, no spécimen being quite complète, 

 were it not for the peculiar locality. 



Fam. Neritidae. 

 Neritina Lamarck. 



1. Neritina (Neritaea Auriculatae) transversecostata n. sp. PI. VI, fig. 4. 



Shell very convex, strongly compressed at the posterior part, yellowish-brown, with 

 black lines, which form more or less conspicuous meshes and in a few cases leave unmarked 

 zones; sculpture consisting of very fine growth-striae and similar spiral striae, which under a 

 strong lens hâve the appearance of spiral rows of granules, moreover the shell is transversely 

 costate, no two spécimens seem to be quite the same, in one spécimen the ribs are nearly lacking, 

 in the other extrême the ribs amount to more than 20, thèse ribs may be lacking on some 

 parts or be regularly spaced. Aperture with columellar area elongate, rounded anteriorly, 

 upper and basai margins slightly convex, upper auricle nearly rectangular with rounded angle, 

 lower one forming a blunt angle, columellar area greyish-white, dull, with a few irregular, 

 shallow grooves, its margin slightly concave, often with very inconspicuous denticles, its 

 posterior margin slightly convex, with the small apex surpassing it and in most spécimens 

 much eroded. Operculum whitish, often with a more or less extensive grey spot towards the 

 columellar side and sometimes a small grey spot near the nucleus, a large, faint reddish 

 border to the right side; left half of outer surface with small granules, right half with curved, 

 rib-like striae, inner surface smooth and shining, similarly coloured, but more yellowish; clavi- 

 form apophysis whitish, with a shallow groove near the end, apical apophysis depressed, yellow. 



Alt. 8, diam. maj. 13 1 /.,; apert. lat. 11, of which 5 '/ 3 for the area. 



New Guinea. Lorentz River, May and May 11, 1907; Sept. 5 — 12 1909. Creek near Bivak 

 Island, May n, 1907. 



This species differs in shape from the majority of known species, but especially by the 

 transverse ribs, which I hâve not found in any description of allied species, and which, though 

 very variable in number, are very conspicuous and so at once distinguish it, for though in 

 one spécimen they are scarcely traceable, this one may be old, with only one or two ribs, 

 which are perhaps rubbed off. 



2. Neritina (Neritaea Mitridae) crepidularia Lamarck. 



Lamarck. An. s. vert. Ed. II. Vol. VIII, p. 572. 



v. Martens. Martini-Chemn. Conch. Cab. Ed. II, Neritina, p. 37, PI. 7, fig. 1 — 14. 



Tapp. Canefri. Fauna Mal. New Guinea, p. 63. 



Tryon. Man. of Conch. Vol. X, p. 77, PI. 23, fig. 95 — 100. 



v. Martens. Sûss- u. Brackw.-Mollusken, p. 218. 



New Guinea. Merauke, 1906. (Dr. Koch leg.) 



The numerous spécimens are dead shells, much bleached, with the columellar area 

 consequently white or yellowish-grey, the colour-pattern is very variable, some spécimens with 



