aoine new aiiJ j)tcu/inr Mollusca. 431 



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

 a space is left on the outer sides ot" the hinge-j^late between 

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

 trianguhir and large. L. 0-15. B. 0-22;5. 



Station 12, 14;">0 fnis. ; a single but large specimen. 

 ' porcupine' Kxj)., 1.SG9, 420-1470 tins.; 1.S70, Bay of liiscay, 

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

 (Segucnza) ! 



Its nearest ally is L. frigida\ but that species wants the 

 peculiar sculpture and ei)idermis, as well as the drooping of 

 tiie posterior side and intlcntation below the angle of L. j/ustu- 

 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 *, JeflFr. 



8hi:ll transversely oval, nearly equilateral, compressed, 

 thin, semitransparent, and glossy : scidjHure, rmmerous 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 : marfjins nearly 

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

 sj)read out and equally rounded at each side, and semicircular in 

 front: leaks central, prominent, and calyciform: lumde 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 stride; margin plain: scars indistinct. 

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



Station 9, 1750 fms. ; 12, 1450 fms. ; 13, 690 fms. : one 

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

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

 1180-1380 fms. 



Differs from L. lucida in being nmch smaller and more 

 compressed ; and the posterior side is rounded instead of pointed 

 and angular. 



Leda lata f, Jeffr. 



Shell forming a short oval, with an oblique contour, 

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

 ture, none except slight irregular lines of growth : colour 



♦ Spread luit. t Hroad. 



