NO. 2134. NOTES ON CHRYSODOMUS—DALL. 223 



Mr. Hanna finds that in Volutopsius and Pyrolofusus the radula 

 is contained in a long sac below the esophagus and separated from 

 it by a thick muscular septum. It emerges by a small orifice near 

 the end of the evertible proboscis, so that on splitting open the pro- 

 boscis no radula is visible. In Ghrysodomus and Plicifusus on the 

 other hand, the radula lies on the lower side of the esophageal tube 

 covered only with a thin, not muscular, membrane. In Beringius 

 {Kennicottii Dall) the radular sac is of the Chrysodomoid type. 



Genus PYRULOFUSUS Morch. 



Fyrulofitsus (Beck Ms.) Morch, Mem. Soe. Malac. de Belgique, vol. 4, 1869, 



p. 20. Sole example, Fusus deformis Reeve. 

 Pirulofnsus Cossmann, Essais Pal. Comp., vol. 4, 1901, p. 98, as synonyn^ 



of Ghrysodomus. 

 Heliotropis Dall, Proc. Cal. Acad. Sci., vol. 5, April, 1873, p. 61. Type. 



Neptunea harpa Morch. 

 Pyrulofusus Fkiele, Jahrb, Mai. Ges., vol. 6; 1879, p. 280; N. Atl. Exp. 



1882, vol. 1, p. 8, pi. 1, fig. 8; pi. 4, figs. 11-13.— Fischer, Man. de 



Concliyl, 1884, p. 624. — Dautzenberg and Fischer, Res. Camp. Scien- 



tifiques de Monaco, 1912, p. 67. 

 Pyrolofusus Krause, Arch. f. Naturg., vol. 51, 1885, p. 282; Zool. Jahrb.. 



vol. 6, 1892, p. 362.— Friele and Greig, N. Atl. Exp., vol. 3, 1901, p. 



102.— Dall, Proc. U. S. Nat. Mus., vol. 24, No. 1264, 1902, p. 523. 



Shell large, relatively thin, with a very short spire and large body 

 whorl, usually sinistral but with rare dextral individuals; nucleus 

 very large, smooth, flat-topped, infolded with an apical dimple, 

 subsequently spirally sculptured, with obscure axial folds; perios- 

 tracum thin, dehiscent; aperture ample, the outer lip expanded and 

 thickened, the body and pillar enameled, often brightly colored; 

 the canal very short, shallow and wide, hardly recurved and with no 

 evident siphonal fasciole; operculum much smaller than the aper- 

 ture, rounded-quadrate with apical nucleus: radula chrysodomoid 

 but rather irregular, the rhachidian tooth in the typical species 

 tricuspid; the laterals with two large terminal cusps, the median 

 cusp of the centra] tooth variable. Ovicapsules as in Volutopsius, 

 large, solitary, and hemispherical, with few embryos. I have dex- 

 tral specimens of both the sinistral species ; an Arctic Pliocene form 

 is dextral. P. harpa Morch, has two strong cusps on the rhachidian 

 tooth and two on each lateral. According to Friele the middle cusp 

 of the rhachidian tooth in P. deformis is quite irregular. The Fusus 

 contrarius is not a member of <^his genus, but merely a reversed 

 species of Ghrysodomus . 



Genus BERINGIUS Dall. 



Beringius Dall, Sci. Expl. Alaska. 1879, pi. 2, figs. 1, lo-c. Sole example. 

 Ghrysodomus crehricostatns Dall, Proc. U. S. Nat. Mus., vol. 9, 1886, 

 p. 304; vol. 7, 1894. p. 710; voV 24, No. 1264, 1902, p. 529, pi. 35, fig. 1. 



