THE CYODOPHORID LAND MO'LLUSKS OF AMERICA 225 



except that on the posterior portion the malleations form several 

 more or less impressed lines. The umbilical wall is rough and shows 

 less of the malleation. Aperture circular with a slightly obtuse angle 

 at the posterior angle ; peristome simple ; that of the outer lip thin, 

 while the inner is thickened and continues as a heavy callus over the 

 parietal wall, which renders the peritreme complete. 



The type, U.S.N.M. No. 307416, was collected by Cuming in 

 Colombia. It has 4.3 whorls and measures: Height, 19.3 mm.; 

 greater diameter, 30.2 mm.; lesser diameter, 20.8 mm. Height of 

 aperture, 12.5 mm. ; diameter, 14.8 mm. 



This species comes nearest to A. (A.) umUlicatum in strength of 

 the malleations and roughness but is easily distinguished from that 

 by its slightly more elevated form, weaker sculpture, and much nar- 

 rower umbilicus. 



APEROSTOMA (APEROSTOMA) PAEZENSE, new species 

 Pl,ATE 31, FlGtTRES 7-9 



Shell very depressed-helicoid ; the denuded nuclear whorls reddish ; 

 the rest of the postnuclear whorls are covered by a rather thick 

 periostracum, that of the first whorl being olivaceous brown, while 

 the last whorl is dark chesnut brown. There is a slender narrow 

 zone of pale olive yellow immediately above the peripheral keel. 

 There is a very broad almost blackish brown zone occupying the 

 peripheral keel and about one-fourth of the base anterior to the 

 keel. A second similar dark narrow zone is separated from the 

 broad one by a moderately broad space. The rest of the base is paler 

 than the upper surface; interior of aperture bluish white. The 

 nucleus consists of a little more than 2 small, well-rounded, smooth 

 turns. The postnuclear whorls are well rounded, the last one slightly 

 flattened toward the suture, dropping a trifle below the periphery 

 on the last fifth of the last turn. The first postnuclear whorl is 

 marked by feeble retractively slanting lines of growth, which gain 

 in strength on the next turn, where they are a little heavier than 

 hair lines and irregular in distribution and development. On the last 

 turn fine malleations and scratches appear, in addition to the above 

 sculpture. Suture well impressed. Periphery weakly angulated. 

 Base broadly openly umbilicated, slightly inflated, well rounded, and 

 marked by the continuation of the lines of growth which assume the 

 strength of riblets on the umbilical wall. Aperture irregularly tear- 

 shaped, decidedly oblique, drawn into an angle at the posterior angle 

 and somewhat angulated at the junction of the basal and outer lip ; 

 peristome simple ; the outer lip thin ; the inner thickened and reflected. 

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



