184 M. M. SCHEPMAN, LAND- AND FRESHWATER MOLLUSCA ETC. 



part of the posterior margin, not on the posterior part of upper margin until the umbones, 

 also the colour is différent, being greenish instead of blackish-brown, as it should be according 

 to DESHAYES (Proc. Zool. Soc. London, 1854, p. 17), moreover the sculpture is more regular, 

 than it should be in divaricata. SûWERBY has located that species in the genus Batissa, which 

 is obviously a mistake, as may be seen by the description of the latéral teeth by DESHAYES ; 

 they are short and not crenulate. The shells vary in size, the largest spécimen has a length 

 of '96, a height of 91 and a ^diameter of 58 mill., they vary slightly in shape, some spécimens 

 being a little more elongated. I think thèse différences are not sufficient to name a new variety. 



2. Cyrena coaxans Gmelin. 



Gmelin. Syst. Nat. Ed. XIII, p. 3278. 



v. Martens. Sûss- u. Brackw.-Mollusken, p. 98, PL 6, fig. 1 — 3. 



New Guinea. Mimika, Febr. 19 10. 



Amongst the spécimens of C. viridescens I find one spécimen which is différent and 

 which after comparison, agrées in so many particulars with the species described and figured 

 by V. Martens (1. c.) as coaxans, that I think it ought to be united with that form ; it is 

 slightly higher in proportion to its length, the height being 83, the length 90 mill., but if one 

 compares the measurements given by V. MARTENS (1. c. p. 99), his spécimens are also variable 

 in this respect, moreover the umbones are not eroded, only the epidermis of the umbones is 

 rubbed off, the posterior margin is still straighter than in the figuré of V. Martens. This 

 species has, as far as I ara aware, not yet been recorded from New Guinea, but I cannot 

 identify it with any of the known species, enumerated by CANEFRI or other authors on its 

 molluscan fauna, and the différences with coaxans are of little importance. 



3. Cyrena kochi n. sp. PI. VI, fig. 7. 



Shell ovate, moderately inaequilateral, with a brown epidermis, which near the ventral 

 margin is lamellose, surface with irregular, partly rather crowded striae and a few impressed 

 grooves, interior light bluish-white; umbones rather prominent, anterior upper margin rather 

 straight at first, then more convex, posterior one convex, ventral margin moderately convex, 

 straighter towards the middle part, strongly rounded at the ends and running with rounded 

 outlines, without prominent angles or truncation into the upper margins. Lunule oval, marked 

 by a shallow line. Right valve with three cardinal teeth, the anterior one short, compressed, 

 triangular, the second and third ones elongate, oblique, moderately thick, each with a groove 

 at the top, the posterior one by much the longest, laterals two at each side, of the anterior 

 ones the interior tooth, if seen from above, forms a long, curved wall, with a slightly elevated 

 point in the side-view, exterior one short, oval, less elevated ; posterior laterals rather distant 

 from the cardinals, interior one straight, little elevated, with a blunt point, exterior one 

 elongated, much shorter. Left valve with three cardinals, the anterior two short, compressed, 

 oblique, with a groove at the top ; anterior latéral short, thick, with a rounded top, connected 

 to the first cardinal by a thick ridge, posterior latéral elongate, compressed, bluntly triangular 

 in the side-view. Muscular impressions conspicuous, shallow, palliai line conspicuous, margin 

 of shell thickened. Ligament but slightly prominent. 



