sonic ntir (1/1(1 j)C(u/i(ir Mulltitica. 331 



Pleurotoma eleyans^ ^loller. 

 Defrancia elvijans, Miill. Iiid. Moll. (}ra»nl. p. 115. 



Body milk-wliitc. Auinuil slut^gish or sliy. 



Godhavn, 5-20 fms. ; Station 5, 57 fins. ; Holstcinborg, 

 10 fni.s. Greenland (Miiller and others)! Gulf of 8t. Law- 

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

 (Leekenby), as P. chujantiur of S. V. Wood! 



yiy largest sjx'eimen is ^^*, of an ineli long. 



Through the kindness of Dr. Morch and Professor Loven 

 I have had the advantage of examining and eomparing the 

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

 that I cannot adopt the view whieh Professor G. O. Sars 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 Holsteiuborg. Of course, 

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

 tion which se{)arate one species from another in any genus, 

 and likewise as regards allied genera. Pleurotoma has been 

 divided by some modern conehologists and paleontologists 

 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. cinercd 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. declicis ; 

 there are at least twice as many s])iral strife, and the sculpture 

 is never cancellated, as in P. dech'ris. 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 striic are fine and close-set. 



Pleurotoma turricula, Montagu. 

 Murex turricula, Mont. Test. Brit. (1), p. 202, t. 9. f. 1 (1803). 



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

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

 ]Melville Bay to Cape Cod, and Spitz])ergen to Areachon. 

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

 Ked and Norwich Crag, and in all the ])Ost-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 North 

 Atlantic, and after a careful cxailiiuatioii and comparison of 



