MOLLUSCA. 



V.-LAMELLIBRANCHIATA. 



By EDGAR A. SMITH, I.S.O. 

 (Plates II. and III.) 



CUSPIDARIA TENELLA. 

 (PI. II., figS. 14, 14a.) 



SHELL rather large, very thin, considerably convex, broadly rounded in front, 

 narrowly or rather shortly rostrate posteriorly, whitish, covered with a thin perios- 

 tracum, sculptured with distinct lines of growth and concentric waves ; inner surface 

 smooth, but concentrically sulcate, the shallow sulci corresponding with the external 

 waves ; dorsal margin of right valve delicate, with a small ligamental pit (see fig. 14a) 

 directed obliquely backwards beneath the umbo, a raised ridge extends from this 

 ligamental process, parallel with the edge of the valve, and might be regarded as a 

 posterior lateral tooth ; adductor scars and pallial sinus indistinct. 



Length, 30 millim. ; alt., 22 ; diam., 15. 



Off Coulman Island, 100 fathoms. 



This is a large species, but very thin, and somewhat resembles C. optima, Sowerby, 

 from South Africa. It is, however, somewhat different in form, is much more delicate 

 in substance, and the ligamental pit and hinder lateral tooth are different. Only a 

 single right valve was obtained. 



ANATINA ELLIPTICA. 



(PL III, fig. 3.) 



Anatina eUiptica, King and Broderip : Smith, ' Challenger,' Lamellibranchiata (1885), p. 76 ; id. ' Southern 

 Cross,' Mollusca, p. 210, pi. xxv., figs. 9, 10. 



Winter Quarters, 10-130 fathoms. 



To show the variation in form, a figure is now given of a short example, which is 

 very different from that figured in the ' Southern Cross ' report. 



THRACIA MERIDIONALIS. 



Thracia meridionalis, Smith, Lamellibranchiata, ' Challenger ' Exped., p. 68, pi. vi., figs. 4-4b. 



Holes 4, 12, etc., 20-130 fathoms. 



The largest specimen obtained exceeds the dimensions of any of the ' Challenger ' 



