PLEUROTOMARIID.E. 69 



the ribs are very close. It then assumes its normal sculpture, but 

 there is nearly a whorl before there is any trace of incision. This 

 appears to have begun as a slit, which was afterwards closed up. A 

 band, marked off by ten transverse ribs showing stages of growth, 

 encircles the shell as far as the hole, which is long and somewhat 

 rectangular ; but there is no band between the hole and the outer 

 lip. The shell furnishes a complete transition to Rimula. (P. P. 

 Carpenter.) 



Mazatlan. 

 Scissurella rimuloides CPE., P. Z. S. 1865, p. 271. 



Family PLEUROTOMARIIDJE Dall. 



Shell trochoidal, nacreous within, umbilicate or imperforate, hav- 

 ing a slit or sinus in the outer superior margin of the peristome, 

 which serves the purpose of an outlet for the anus, and leaves on the 

 corresponding part of the whorls a peculiarly sculptured baud, the 

 " anal fasciole" or " slit fasciole." 



Animal without frontal lobes or appendages ; eyes at the outer 

 bases of the tentacles ; muzzle as in Trochida? ; tentacles long, sub- 

 cylindrical, bluntly pointed. Epipodium broad, thin, entire, fringed 

 with a row of small, short papillae, but not bearing cirri, closely ap- 

 plied to the shell. Radula long ; rhachidian tooth narrow, lanceo- 

 late, its tip narrow, recurved ; laterals 26, the outer 5 without cusps ; 

 the inner ones larger, with wide cusps and narrower bases. Outside 

 of the laterals are 2 rows of unciui, the inner series about 18 in 

 number, large, strongly curved, with scythe-shaped 1-3 denticulate 

 cusps ; outer uncini very numerous (40-50), small, very oblique. 

 (P. quoyana.') In P. adansoniana there are considerable differences 

 in the teeth ; some of the uncini bearing little tufts of bristles at 

 their apices. Jaws subobsolete. 



Genus PLEUROTOMARIA Sowerby, 1821. 



Pleurotomaria J. SOWERBY, Mineral Conchology iii, p. 139, t. 

 278, Dec. 1821. Pleurotomaire DEFRANCE, Tabl. des. Corps Foss., 

 p. 114, 1824 (no descr.). Pleurotomaria Defr. J. de C. Sowerby, 

 Min. Conch, vii, p. 69, t. 640, Nov. 1844. CROSSE, Journ. de Con- 

 chyl. 1882, p. 1. FISCHER Manuel de Conchy]., p. 849, 1885. Pleu- 

 rotomaria Sowb., DALL, Bull. Mus. Comp. Zool. xviii, p. 396. 



Dr. Dall has satisfactorily shown that the name Pleurotomaria 

 should be attributed to James Sowerby, not to Defrance, who never 

 denned nor latinized his " Pleurotomaire." 



