Chaster — On the Mollusca obtained by the M.I.A. Cruises. 19 



OnosTOiiiA cois"oiDEA, Broechi, sp. (Turho). 



Station YII. Logs 3, 9, 11, 12, 18, 21, 28, 31, 33, 42, 

 50, [55] ; depth, 4 or 7 to 808 fathoms. This species, the 

 type of the genus Odostomta, is well represented in the 

 dredgings. 



Var. AUSTKAiis, Jeffreys. 



Log 33. A single specimen. 



Although I am quite convinced of the propriety of subdividing 

 the group of shells which Jeffreys included in the genus Odosto- 

 mia, none the less do I agree in the main with his last remarks 

 on the subject which appeared in the "Porcupine" Eeports. 

 Par too great value has been placed upon solitary characters, 

 such as the presence or absence of sculpture or of columellar fold. 

 I have specimens of Pyrgiilina indistincta, Montagu, from Salona 

 Bay, Greece, showing gradations from typically sculptured shells, 

 to others quite smooth. In some species, e.g., Eulimella com- 

 mutata, Monts., the columellar fold is very variable as to its 

 presence or absence. Obviously, then, characters such as these, 

 which are not of specific value, cannot furnish bases for generic 

 subdivisions when taken alone. But the peculiarities of the 

 fold and sculpture, when taken in conjunction with other 

 characters, as the form of tlie shell, the conformation of the 

 apex, the sinuation of the outer lip, afford good ground on 

 which to build. 



O. coNSPicuA, Alder. 



[Station VII.] Logs 30, 33. Young specimens only. 



O. TTMBiLiCAEis, Malm, sp. {TurhoniUa). 



Log 42. A single specimen. I strongly suspect that this 

 species is little more than a local variety of the next. 



0. ACUTA, Jeffreys. 



Station YITI. Logs 9, 11, 28, 42. 



0. PLiCATA, Montagu, sp. {Turho). 

 Logs 35, 62, E, 



0. TTTEEiTA, Hauley. 



Logs 6, 28, 35, 63. 



Va/r. NANA, Marshall. 

 Log 42. 



C 2 



