250 BULLETESr 181, TJNTTEiD SWATElS NIATTONIAIL MUSEUM 



U.S.N.M. No. 366106 contains an additional specimen from Quito ; 

 U.S.N.M. No. 126907, one specimen collected by M. B. Kerr is 

 labeled merely "Ecuador." 



This species, which has the same type locality as A. {A.) ecuador- 

 ense, is of about the same size as that species but is more depressed, 

 with a much larger umbilicus. 



THE GROUP OF APEROSTOMA (APEROSTOMA) QUITENSE 



Medium-sized shells, not decidedly depressed and having a rather 

 large aperture. 



APEROSTOMA (APEROSTOMA) QUITENSE (Pfeiffer) 



Plate 36, FiGtrsEvS 13-15 



1852. Cyclostoma {Cyclotus) quitense Pfeiffer, Proc. Zool. Soc. London, vol. 



20, p. 61. 

 1852. Cyclotus quitensis Pfeoter, Monographia pneumopomorum viventium, 



vol. 1, p. 17. 

 1854. Cyclostoma quitense Pfeiffer, Martini-Chemnitz Conchylien Cabinet, vol. 



1, sect. 19, p. 340, pi. 44, figs. 19-22. 

 1897. Neocyclotus (Neocyclotus) quitensis Kobelt and Moixendorff, Nachrb. 



deutschen malak. Ges., vol. 29, p. 138. 

 1923. Poteria (Neocyclotus) quitensis H. B. Baker, Occ. Pap. Mus. Zool. Univ. 



Michigan, No. 137, p. 43. 



Shell rather large, low, helicoid, covered with a bright chestnut- 

 brown periostracum. There is a pale, rather broad zone immediately 

 above the periphery. The base is bicolor, having a broad, very dark 

 chestnut-brown band immediately below the periphery, which ex- 

 tends over half of the base. The anterior half of the base, including 

 the umbilical wall, is bright horn color ; interior of aperture decidedly 

 bluish, showing the external banding within. The nucleus consists 

 of 2 well-rounded, smooth turns. The postnuclear whorls are well 

 rounded, the last one is slightly impressed a little below the suture. 

 They are marked with weak, retractively curved axial riblets. Suture 

 strongly impressed. Periphery well rounded. The light band above 

 the periphery produces an optical illusion of angulation. Base mod- 

 erately broadly umbilicated, inflated, strongly rounded, and marked 

 by the continuation of the feeble riblets on the posterior half, but from 

 there on these riblets become much strengthened and are quite strong 

 on the umbilical wall. Aperture broadly oval, with a rather strong 

 auricle at the posterior angle; peristome simple; outer lip rather 

 flaringly expanded and slightly reflected; inner lip somewhat thick- 

 ened. The parietal wall is covered by a thick callus, which renders 

 the peritreme complete. The operculum is typically aperostomid, 

 showing: 9 whorls. 



