320 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



APORRHAID^E. 



Genus APORRHAIS, Dillwyn. 



Synon.— Aporrhais, Dillwyn (1823), Philos. Trans., II, 395.— Gray (1835), ib., 305; and (1847) Trans. Zool. 

 Soc. Lond., 136— Swainsou (1840), Malac, 141 and 309.— G. B. Sowerby, jr. (1842) 

 Thes. Conch., I, 21; and Conch. Man. (2d ed.), 71. — Forbes aud Hanley (1853), Hist. 

 Brit. Moll., Ill, 185.— H. and A. Adams (1854), Genera Recent Moll , I, 281.— Gabb 

 (1868), Am. Jonr. Conch., IV, 143.— Stoliczka (1868), Palseont. Indica, II, 23 and 447.— 

 Gould and Binney (1870), Invert. Mass. (2d ed.),' 320.— Tryon (1873), Am. Marine 

 Conch., 17 (not Aldrovandi, Gualt. and Klein). 



Chenopus, Phillipi (1836), Moll. Sic, 214.— Koch and Dunker (1837), Beitr. Verst. Nord. Oolite, 

 34.— Bronn (1838), Leth., 1088.— Munster( 1839), Beitr. Petref., 1, 98.— Deshayes (1843), 

 Lamarck (2d ed.),IX,656. 



Alipes, Conrad ( 1865), Am. Jour. Conch., 1, 31 (as a subgenus under Aporrhais). 



Goniocheila, Gabb (1868), Am. Jour. Conch., IV, 144 (proposed as a subgenus under Aporrhais). 



Arrhoges, Gabb (1868), ib., 145 (proposed as a subgenus under Aporrhais). 



Etym. — axopp/'/yvv/it, to tear apart. 

 Type. — Strombus pi s-pelicani, Linuajus. 



Shell never attaining a large size, more or less fusiform before maturity, 

 but in the adult with outer lip thickened, expanded, and produced into from 

 one to three pointed digitations, or sometimes with only one obtuse lobe-like 

 projection, generally sinuous anteriorly ; inner lip callous ; aperture provided 

 with a posterior canal extending more or less upward, and terminating ante- 

 riorly in a canal of variable length and form, according to the sections and 

 species; surface variously ornamented with folds, costae, nodes, and striae, 

 or rarely cancellated. 



The foregoing synonymy and diagnosis are intended to include three sec- 

 tions, distinguished as follows : 



1. aporrhais, Dillwyn (typical, — C/ienojws, Phill.). 



Shell with the expanded outer lip produced into two or three 

 angular digitations which are furrowed within, and carinate externally ; 

 posterior canal produced up the spire, and free at the extremity ; 

 anterior canal rather produced, somewhat expanded or narrow, and 

 curved or straight. — (Type as already stated.) 



2. alipes, Conrad (— Goniocheila, Gabb). 



Shell with posterior canal extending about half way up the spire, 

 and not free at the end ; expanded outer lip with only one projecting 

 angular process, but bearing one or more external carina in front of 

 this that do not terminate in marginal digitations; canal short and 

 strongly incurved; inner lip thick. — A. liratus, Conrad. 



