some neio and 2)ecu Ua r Mo llusca . 43 1 



side, including 3 or 4 minute tubercles close to the cartilage ; 

 a space is left on the outer sides of the hinge-plate between 

 the margins and the teeth : inside smooth and polished: scars 

 triangular and large. L. 0*15. B. 0*225. 



Station 12, 1450 fms. ; a single but large specimen. 

 'Porcupine' Exp., 1869,420-1470 fms.; 1870, Bay of Biscay, 

 202-740 fms. Fossil in the Zanclean formation at Messina 

 (Seguenza) ! 



Its nearest ally is L. fn'gida ; but that species wants the 

 peculiar sculpture and epidermis, as well as the drooping of 

 the posterior side and indentation below the angle of L. pustu- 

 losa : its teeth are very much smaller, and they do not extend 

 so far on the hinge-line. From L. acuminata (or Messanen- 

 sis) it also differs in being more shortly oval, and having the 

 posterior angle obtuse instead of acute. 



Leda expansa *, Jeffr. 



Shell transversely oval, nearly equilateral, compressed, 

 thin, semitransparent, and glossy : sculjpture^ numerous slight 

 but regular concentric strise, which are observable only by 

 means of a lens and disappear towards the beaks ; there are 

 also faint traces of microscopic lines radiating from the beaks 

 to the front : colour pale yellowish-white : margins nearly 

 straight at the back except for the projection of the beaks, 

 spread out and equally rounded at each side, and semicircular in 

 front: healxs central, prominent, and calyciform : lunule forming 

 a sharp ridge : ligament inconspicuous or wanting : cartilage 

 and pit very minute, the latter sunken : hinge-line very gently 

 curved : hinge-plate rather broad : teeth small, recurved, 7 or 

 8 on each side of the beak : inside polished, showing faint 

 traces of the longitudinal strias; margin plain: scars indistinct. 

 L. 0-1. B. 0-175. 



Station 9, 1750 fms. ; 12, M50 fms. ; 13, 690 fms. : one 

 living and a few more or less perfect specimens. ' Porcu- 

 pine ' Exp., 1869, off the north-western coast of Ireland, 

 1180-1380 fms. 



Differs from L. lucida in being much smaller and more 

 compressed ; and the posterior side is rounded instead of pointed 

 and angular. 



Leda lata f, Jeffr. 



Shell forming a short oval, Avith an oblique contour, 

 rather convex and solid, transparent, and highly glossy : sculp- 

 ture, none except slight irregular lines of growth : colour 



* vSpread out. t Broad. 



