NO. 2134. NOTES ON CHRYSOBOMUS—DALL. 221 



It is possible that some of the species included under Parvisipho 

 Cossmann might find a place here. 



Section HELICOFUSUS Dall. 



Shell small, short, inflated, with an external chalky layer covered 

 with a dark rude periostracum, both usually eroded ; the inner shell 

 layer of an orange color; nucleus large for the shell, depressed, dome- 

 like, smooth and of about one whorl; the succeeding whorl or two 

 with short small axial ribs, the later whorls with only fine spiral 

 sculpture, usually eroded; aperture as long as the spire: outer lip 

 fcharp, flexuous behind, not reflected; body and pillar with a thin 

 callus; pillar short, twisted, abruptly bent to the left with the wide 

 short canal, no siphonal f asciole present ; operculum as in Plicifusus. 



Type. — Chrysodomus laticaudatus Dall. Alaska U. S. Nat. Mus., 

 Nos. 210801 and (nucleus) 213357. 



The remarkable way in which the canal is diverted from its normal 

 direction, seems to place tliis species in a group apart. The large 

 number of specimens collected, though showing some variation, are 

 constant enough to indicate that the deflected canal is a permanent 

 feature. The tendency to superficial erosion is also characteristic. 



Genus EXILIA Conrad. 



Exilia CoNBAD, .Tourn. Acad. Nat. Sci. Phila., n. ser., vol. 4, p. 291, 1860. 

 Type. E. pergracilis Conrad, Joiu-n. Acad. Nat. Sci. Phila., vol. 4, 1860, 

 pi. 47, fig. 34. Eocene of Texas. 



Shell elongate, very slender, with numerous whorls, chrysodomoid 

 nucleus, and a straight canal; periostracum conspicuous, polished; 

 sculpture of numerous fine flexuous axial ribs and spiral striation; 

 aperture small, simple, not lirate within, outer lip thin, sharp, not 

 reflected ; inner lip and pillar smooth, without plications or denticles 

 of any sort; operculum long, slightly arcuate, with apical nucleus. 



This shell has the nucleus and periostracum of Plicifusus but much 

 the form of Fwsinus^ of which Gabb's Exilifusus is a synonym. A 

 curious error appears in Cossmann's Essais de Paleoconchologie com- 

 paree, (livr. 4, 1901, p. 26,) in which Exilia is described as having 

 two oblique plaits on the pillar. There are none of any kind what- 

 ever. M. Cossmann's specimen was probably wrongly identified with 

 Exilia^ and may have been a Fusiinitra. 



Ckrysodomus rectirostris Carpenter, and C. kelseyi Dall, appear 

 to belong to this genus, which is also represented in the Pliocene of 

 California. 



Genus VOLUTOPSIUS Morch. 



Volutopsius Morch, Fort. ov. Gi'onl. Bloddyr., April, 1857, p. 13; Article 

 Manual, 1875, p. 129. Type, Fusus largillierti Petit. Greenland. 



Strombella Gray, Guide Moll. Brit. Mus., Jan. 1857, p. 13. Type, Strciiibus 

 norvegicus Gmelin. Not Strombella Schliiter, Syst. Conch. Samml., 

 1838, p. 22. 



