A. E. Verrill — Mollnsca of the Nexo England Coast. 289 



The different groups of mollusca differ greatly in the relative pro- 

 portion of deep and shallow-water species, as shown by the following 

 tables. Thus the deep-water Cephalopods are 23, against 4 shallow- 

 water and surface species. The Gastropods exclusit^ely deep-water 

 are 166, against 38 of shallow-water origin. The shallow-water La- 

 mellibranchs, however, seem to have a much greater tendency to 

 range into deep-water, for of these there are but 68 deep-water species, 

 associated with 46 shallow-water ones. 



The species and varieties described as new, in this paper, are V2, as 

 follows : Cephalopoda, 4 ; Gastropoda, 56 ; Solenoconcha, 3 ; Lamel- 

 libranchiata, 9. The total number of species of mollusca added to 

 the fauna of this region by the Fish Commission dredgings, since 

 1880, is about 300, but only 276 of these are included in the above 

 list; of these 121 were obtained in 1883. 



Among the peculiarities of the deep-water mollusca the occurrence 

 of an unusual proportion of Toxoglossa, many of which are hand- 

 somely sculptured and of large size, is a noteworthy feature. Tecti- 

 branchs are also abundant and some of them large. Rhiphidoglossa are 

 also relatively abundant and present some striking and elegant forms 

 of Trochidas, while there are 13 limpet-like forms belonging to this 

 group, including the genera Coccidina, Addisonia, Lepetella, Pro- 

 pilidium. The Solenoconcha or Scaphopoda are relatively much 

 more abundant, and some of the species are much larger in 500 to 

 2000 fathoms than in shallow-water. This must be regarded as 

 mainly a deep-sea group. 



Among Lamellibranchs the groiips that are relatively most num- 

 erously represented are the Anatinidcne and Corbulida^, (especially the 

 genus Neaera) ; the Nuculidte, including the genera Niicula, Leda, 

 Yoklia, Malletia Glomus, etc. ; and the Arcida?, including Area and 

 Limopsis. The Lucinidse and Pectenidoe are also well represented. 



