198 BULLETIiN 181, UNITED SiTATElS NIATTOIISPAjL MUSEUM 



As we have not seen this species we give a translation of Da Costa's 

 description and copy his figure. 



Shell openly umbilicated, depressed, yellowish. Whorls 4.5, rounded, 

 marked by incremental striae and obscure retuse corrugations. Peri- 

 stome thin, simple, the margins joined by a callus. Operculum testa- 

 ceous, closely wound with a threadlike carina at the suture, the middle 

 concave. Altitude, 10 mm. ; greater diameter, 15 mm. ; lesser, 12 mm. 

 [The aperture of Da Costa's figure gives the following measure- 

 ments ; Height, 6.6 mm. ; diameter, 6.4 mm.] 



Habitat: Chiriqui, western Panama. 



The very broad umbilicus figured by Da Costa differentiates this 

 from the other members of the group. 



APEROSTOMA (AUSTKOCYCLOTUS) STRAMINEUM (Reeve) 

 PLA-ra! 27, FiGUEES 9-11 



1843. Cyclostoma stramineum Reeve, Proc. Zool. Soc. London, vol. 11, p. 46. 

 1843. Cyclostoma stramineum Sowekby, Thesaurus conchyliorum, vol. 1, p. 93, 



pi. 29, figs. 211-212. 

 1852. Cyclotiis stramineus Pfeitfee, Monographia pneumonopomorum viventium, 



vol. 1, p. 20. 

 1897. Neocyclotus (Neocyclotus) stramineus Kobelt and Mollendobff, Nachrb. 



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

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



Michigan, No. 137, p. 37, pi. 5, figs. N, O. 



Shell small, depressed-helicoid, unicolor, covered with a buff perios- 

 tracum. The nucleus consists of 2 small, well-rounded, smooth turns. 

 Postnuclear whorls inflated, strongly rounded, appressed at the sum- 

 mit and marked by numerous closely spaced axial riblets, which have 

 a retractive and protractive arrangement, and the junction of which 

 produces slender nodules, which increase in strength with the in- 

 crease of the whorls. At the periphery these riblets have a decided 

 retractive slant. On the last turn those near the suture are a little 

 stronger and a little more protractively directed. Suture very nar- 

 rowly impressed. Periphery well rounded. Base narrowly umbili- 

 cated, inflated, stongly rounded, and marked like the spire. This is 

 also the sculpture of the umbilical wall. Aperture almost circular, 

 protracted into a conspicuous angle at the posterior angle of the 

 aperture ; peristome thin on the outer lip, thickened on the inner lip. 

 The parietal wall is covered by a thick callus, which is slightly sep- 

 arated from the preceding turn. Operculum typically aperostomid, 

 concave in the middle, and having about 6 whorls. 



The specimen figured is one of three, U.S.N.M. No. 316389. It 

 has 4.3 whorls and measures: Height, 13.8 mm.; greater diameter, 

 20.8 mm.; lesser diameter, 15.1 mm. Height of aperture, 8.3 mm.; 

 diameter, 9.9 mm. The type came from Merida, Venezuela. 



