some new and peculiar Mollusca. 331 



Pleurotoma elegans, Moller. 

 Defrmicia eleyans, Moll. Ind. Moll. Groenl. p. 13. 



Body milk-white. Animal sluggish or shy. 



Godhavn, 5-20 fms. ; Station 5, 57 fms. ; Holsteinborg, 

 10 fms. Greenland (Moller and others) ! Gulf of St. Law- 

 rence (Whiteaves) ! Iceland (Torell) ! Fossil at Bridlington 

 (Leckenby), as P. elegantior of S. V. Wood! 



My largest specimen is ^J of an inch long. 



Through the kindness of Dr. Morch and Professor Lovdn 

 I have had the advantage of examining and comparing the 

 types of P. cinerea^ P. declivis^ and P. elegans ; and I regret 

 that I cannot adopt the view which Professor G. O. Sara is 

 inclined to favour, that all these may be one species. I have 

 not yet seen any connecting link between them ; and they all 

 occurred to me in the same haul of the dredge at Station No. 5, 

 in the ' Valorous ' Expedition, off Holsteinborg. Of course, 

 opinions of naturalists must differ as to the lines of demarca- 

 tion which separate one species from another in any genus, 

 and likewise as regards allied genera. Pleurotoma has been 

 divided by some modern conchologists and palgeontologists 

 into a great many genera, although, in my opinion, on insuf- 

 ficient grounds There ought to be at least one distinctive 

 and fixed character, and no transitional or intermediate forms. 

 P. cinerea attains the greatest size ; the whorls are more con- 

 vex, the last is larger in proportion to the rest, and they are 

 not angulated below the suture, as in the other two species ; 

 the longitudinal ribs are more numerous than in P. declivis ; 

 there are at least twice as many spiral strige, and the sculpture 

 is never cancellated, as in P. declivis. The smallest species 

 is P. elegans ; the whorls are abruptly angulated at the tip ; 

 the ribs are more numerous, oblique, and prominent than in 

 P. cinerea, and the strige are fine and close-set. 



Pleurotoma turricula, Montagu. 

 Murex turricttla, Mont. Test. Brit. (1), p. 262, t. 9. f. 1 (1803). 



Godhavn, 5-20 fms. ; Waigat Strait, 15-25 fms. ; Station 1, 

 175 fins. ; 3, 100 fms. ; 5, 57 fms. ; Holsteinborg, 10-30 fms. 

 Melville Bay to Cape Cod, and Spitzbergen to Arcachon. 

 North Japan (St. John) ! Depths 10-150 fms. Fossil in our 

 Red and Norwich Crag, and in all the post-Tertiary beds of 

 Great Britain, Scandinavia, and Canada. 



The sculpture is extremely variable. Having before me a 

 great number of specimens from various parts of the Nortli 

 Atlantic, and after a careful examination and comparison of 



