MARINE MOLLUSKS MACGINITIE 101 



Boreotrophon truncatus (Str^dn, 1768) 



Plate 7, figxires 8-10; Plate 8, figures 3, 4, 7, 9 



Buccinum truncatum Str0m, 1768, vol. 4, p. 369, pi. 16, fig. 26. 

 Trophon truncatus G. Sars, 1878, p. 246, pi. 15, fig. 9. — Morris, 1947, p. 144, pi. 39, 

 fig. 1; 1951, p. 185, pi. 39, fig. 1. 



Because of difficulties in identification, the exact number of speci- 

 mens of this species is in question. Two Hving specimens (17.7 mm. 

 long by 7.6 mm. in diameter, and 16.6 mm. by 7.8 mm.) were taken 

 from 741 feet (pi. 8, figs. 4, 9). Six living specimens (ranging from 

 6.3 to 11 mm. in length) with from 4 to about 5.5 whorls, and with 

 from 12 to 16 varices (the number not dependent on size of shell), 

 were found among a foliaceous bryozoan from 120 feet (Sept. 15, 1948). 

 The smallest of these was practically covered with a colony of encrust- 

 ing bryozoans. 



Also on this foliaceous bryozoan from 120 feet a Boreotrophon meas- 

 uring 13.9 by 7.2 mm. with 5.5 {whorls and with 18 varices was 

 found. The spire of this shell was covered with old hydroid stalks 

 among which were what appeared to be small, irregular, flattish 

 packets of yellowish, oval eggs with a round hyaline dot toward one 

 end. From 217 feet was dredged a similar live shell measuring 11.1 by 

 5.9 mm. with about 5.25 whorls and with 17 varices. The spire of this 

 shell was covered with a growth of Syncoryne (pi. 8, fig. 3). Two living 

 specimens, similar to the two just mentioned, were taken at 184 feet 

 (pi. 8, fig. 7), 1 at 438 feet, and 2, somewhat larger, at 125 feet. 



Ten other living specimens and 5 dead shells, all larger than the ones 

 mentioned above, came from depths of 72 to 438 feet. 



Other material examined: Several specimens from the Jeffrey's 

 collection (now in the U. S. National Museum) ; several in the collec- 

 tion of the U. S. National Museum; 4 from western Greenland (sent 

 by Dr. Thorson). 



Discussion: The 4 specimens from Greenland have about 5.5 

 whorls and 18 varices; they are beige colored, with beige to dark tan 

 throats. By comparison, the Point Barrow specimens are translucent 

 white to chalky white and the throats are white. The smallest Point 

 Barrow specimens mentioned above are slenderer (pi. 8, fig. 7) than 

 the Greenland B. truncatus; the aperture seems a trifle smaller and the 

 canal a little longer than in the Greenland specimens. 



These same differences are apparent between the medium-sized 

 Point Barrow specimens and those from Greenland; in addition, the 

 former have somewhat shorter spires and more rapidly increasing 

 body whorls. 



The same differences are also found in the largest specimens men- 

 tioned above, but in these the canal is even longer, although it is prob- 



