398 PLEUROTOMID^. 



12. P. Trevelya'na^^ [Trevellianum) Turton. 



P. Trevelhiaomvi, Turt. in Mag, N. H. vii. p. 351. Mangelia Trevelliana^ 

 R & H. iii. p. 452, pi. cxii. f. 1, 2. 



Shell approaching P. turricuJa, but essentially distinct. 

 This is smaller, and more oval than oblong ; the spire is not 

 so decidedly and abruptty turreted or scalar ; the whorls are 

 rounded ; the sculpture is very much finer and closer (there 

 being twice as many longitudinal ribs) ; and the whole surface 

 is decussated, in consequence of the ribs and spiral strias being 

 equal-sized and intercrossing ; the second whorl is marked by 

 minute and numerous spiral lines ; the colour is uniformly 

 milk-white ; the canal is shorter ; the labial notch is deeper ; 

 and the operculum has a strong ledge on the inner side, and 

 is microscopically striated (as well as slightly reticulated) 

 lengthwise. L. 0-45. B. 0-2. 



Habitat : With P. turricula in the stomachs of had- 

 docks, Scarborough (Bean); muddy sancl outside the 

 Dogger bank, on the Yorkshire coast, in 50-60 f. (Lec- 

 kenby) ; Durham and Northumberland (Alder and 

 others) ; Berwick Bay (Mennell) ; Firth of Forth (M 'An- 

 drew) ; Aberdeenshire (Macgillivray and others) ; Eda 

 Sound, Orkneys (Thomas, fide F. & H.); Shetland 

 (Forbes and others) ; west coast of Scotland (Barlee and 

 J. G. J.)- Fossil in the Clyde beds (Brown and Cross- 

 key); Hebrides (J. G. J.); Turbot-bank, co. Antrim 

 (Hyndman and others); boulder-clay, Wick (Peach); 

 Bridlington (Woodward) ; Bramerton (Witliam, fide 

 Woodward); Uddevalla (J. G. J.); glacial deposits in 

 Norway, 50-240 feet (Sars); Canada (Dawson). This 

 species is exclusively northern, and is distributed from 

 Zealand to Spitzbergen, along the coast of Greenland 

 westward to Massachusetts ; west coast of North Ame- 

 rica (P. Carpenter) : depths 8-200 f. 



For my largest specimen I am indebted to my able 



♦ A complimentary dedication to Sir Walter Trevelyan, Bart. 



