some new and peculiar Mollusca. 497 



Necera notahih's*^ Jeffr. 



Shell oval, convex, thin, opaque, somewhat glossy : sculp- 

 ture, none in the nmbonal region (which is quite smooth), but 

 on the anterior side and in front are about 30 fine concentric 

 and equidistant lamellar ridges or stride ; the rostrum on the 

 posterior side is defined by two keels, the lower one slanting 

 and the upper flexuous ; the posterior side is transversely 

 wrinkled in a fibrous manner; the whole surface appears, 

 under a microscope, to be covered with minute and close-set 

 strias, which run parallel to the ridges and obliquely on the 

 posterior side : colour white : margins rounded on tlie anterior 

 side and in front, indented under the rostrum, which is rather 

 short and gently curved at the point, straight behind : beaks 

 small, incurved towards the anterior side; umbones prominent : 

 cartilage narroAV ; pit or receptacle sunk under the beaks : 

 hinge-line nearly straight, except where it is interrupted by 

 the beaks : hinge-jolate narrow and slight, slightly folded back 

 on the upper part of the anterior side in the left valve : teeth, 

 a lateral one on each side in the right valve, both of which 

 laterals are triangular and erect near the beak, and thin off as 

 ridges towards either side : inside glossy, exhibiting the im- 

 pression of the rostral keels : scars indistinct. L. 0*2. B. 0"35. 



Station 12, 1450 fms. ; two valves and fragments. Some 

 of the fragments show that this species attains a larger size 

 than that given in the description. 



Nemra circinata^, Jeffr. 



Shell roundish-oval, obliquely twisted towards the pos- 

 terior side, convex, rather solid, opaque, and of a dull hue : 

 sculpture, scarcely any in the umbonal region, about 25 fine 

 concentric and equidistant lamellar ridges or strige in the 

 middle of the shell, which become confluent in front and dis- 

 appear at the sides ; the rostrum has two keels (as in the last 

 species), which radiate from the beak; the posterior side is 

 also wrinkled transversely ; between the ridges are minute 

 but not numerous concentric strige : margins rounded on the 

 anterior side, sloping with a gentle curve in front (the curve 

 being greatest towards the posterior side), indented at the 

 commencement of the rostrum, straight behind, and somewhat 

 upturned at the posterior end; rostrum triangular, with a 

 curved slope downwards : heaks as in other species ; umbones 

 not so prominent as in the last : cartilage oval ; pit not much 

 sunk below the beaks : Mnge-line nearly straight, but (viewed 



* Remarkable. t Rounded. 



