so7ne new a7id jyeculiar Mollusca. 429 



certainly not internal : lunge-line nearly straight, but obtuse- 

 angled at the hinge : hinge-plate narrow, minutely and closely 

 denticulated on both sides of the hinge : inside polished and 

 nacreous ; edge plain : scars inconspicuous. L. 0'2. B. 0*1. 

 Station 12, 1450 fms. < Porcupine ' Exp., 1869, Bay of 

 Biscay, 994 fras. A single valve from each locality. 



Dacrydium vitreum (Holboll), Moller. 

 Modiola? vitrea (Holboll), Moller, Ind. Moll. Gronl. p. 19, 

 Station 12, 1450 fms. 'Porcupine' Exp., 1869, off the 

 north-western coast of Ireland, 164-664 fms. ; North Sea, 

 345 fms. ; outside the English Channel, 2090-2485 fms. : 

 1870, Bay of Biscay, 386-1095 fms. Greenland (Holboll) : 

 Spitzbergen (Torell) : Loffoden Isles, 200-300 fms. (Sars) : 

 Finmark (McAndrew) : ' Challenger ' Exp., off the Azores, 

 1000 fms.: ' Shearwater' Exp., African coast of the Mediter- 

 ranean, 40-120 fms. : Mediterranean, off Tunis, 30-600 fms. 

 (Nares): Sicily (Stefanis and Monterosato) : fossil at Palermo 

 (Philippi as Modiola pygmcea) . 



Living specimens from 2435 fathoms were enclosed in an 

 agglutinated case of Atlantic ooze mixed with Olohigerince 

 and fragments of sponge, a habit resembling that of ^^ Modiola'''' 

 agglutinanSj Cantraine, = il/. vestita, Philippi. The hinge- 

 plate is crenated, as in Idas, Modiolaria^ and Grenella ; but 

 Dacrydium has a cartilage and corresponding pit. The 

 generic name had long been used for a well-known kind of 

 tree ; so that we have a somewhat inconvenient employment 

 of it in zoology as well as in botany. 



Arcidas. 



Nucula reticulata *, Jeffr. 



Shell extremely convex and nearly globular, rather thin, 

 glossy and semitransparent : sculpture^ numerous and regular 

 fine concentric ridges, which disappear towards the beaks and 

 lunule ; these ridges are crossed by equally numerous but 

 almost microscopic longitudinal striee, so as to give the sur- 

 face a closely reticulated appearance : colour white : eindermis 

 thin, yellowish-white to pale horn-colour: margins sloping on 

 the anterior side to a rather sharp point, rounded and broad 

 (or occasionally flexuous) in front, and wedge-shaped on the 

 posterior side : heaks nearly in the middle of the dorsal area, 

 prominent, and bulbous : lunide triangular and longish : liga- 

 ment conspicuous and strong : cartilage and pit small : hinge- 



* Reticulated. 



