or CONCHOLOGY, 237 



aperture broadly ovate, slightly oblique and subangulated above; 

 peristome broadly expanded, thickest on the outer lip, continued 

 on the body whorl by a plate which becomes a heavy callus in 

 old shells, columella having a very prominent spiral fold in the 

 middle ; umbilicus small ; color, a delicate whitish horn color, 

 lip white ; surface sculptured by irregularly undulating lines of 

 growth crossed by numerous revolving impressed lines, only 

 visible under a magnifier. 



Locality. — Found in the mountains, among rocks from San 

 Antonio, below La Paz, to near San Borja, and in the highest 

 mountains perhaps even farther north. • 



Observations. — This is a strongly characterized species ; the 

 fold in the columella separates it from all of the other species 

 found on the peninsula, and a glance at its exterior is also suffi- 

 cient to distinguish it ; it is one of the slenderest of the group, 

 and the lower part of the body whorl has a peculiar obliquity, 

 setting the mouth off to one side in a manner that can hardly be 

 characterized, except by a figure. 



BuLiMUS VESiCALis, Gould. — Plate 16, fig. 6. 



Found dead in the low lands about La Paz ; no living speci- 

 mens were encountered. The specimens differ a little from 

 Gould's figure. 



Cylindrella (Urocoptis) Newcombiana, Gabb. — Plate 16, 

 fig. 3. 



Description. — Shell moderately large, not decollate, slender, 

 tapering more rapidly below than near the apex, the first three 

 whorls being of the same size ; whorls eleven and a half, flatten- 

 ed on the side, body whorl subangular below, detached from the 

 penultimate whorl for a short distance, and acutely angular 

 above; suture impressed ; aperture slightly advanced and sur- 

 rounded by broadly expanded lips, producing a trumpet- shaped 

 appearance ; inner margin straight, and ending in an angle 

 above and below ; outer margin carved, wider in advance than 

 behind, lips continuous, broadly expanded, and somewhat 

 thickened ; surface light horn color, marked by fine, irregular, 

 undulating and occasionally broken ribs, radiately and obliquely 

 disposed, and with the interspaces crossed by microscopic re- 

 volving lines. 



Animal light grey, equalling in length the aperture and 

 penultimate whorl ; foot short, and regularly rounded posteri- 

 orly. 



