THK NAUTILUS. 129 



lots, of 13 and 5 specimens respectively.' In one lot tlie shells are 

 more conic than the types, with the rib-striaj more delicate and 

 sharp, obsolete on the base. Specimens measure: 



Length 10..'), diam. 5 mm.; 9^ whorls. 



Length 10, diam. ti mm.; 9 whorls. 



Length 9, diam. 4.2 mm.; 9 whorls. 



In the other lot the shells are larger but also sculptured with deli- 

 cate, thin rib-strios, much narrower than tiieir intervals. Length 13, 

 diam. G mm., 10 whorls. This race may be called var. tenuiitriuta 

 (pi. VlII,flg. 14). 



Microcera:mls perconicus trinidadensis, n. var. PI. VIII, 



figs. 15, 17, 18. 



The shell is imperforate, the last two whorls forming a broad, 

 shortly cylindric part, those above rapidly tapering in form of a 

 straigiit-pointed cone, slender above ; rather glossy ; corneou-s-brown, 

 tlie last 4 or 5 whorls nearly covered with patches on which the 

 stria) are opaque white. AVhorls convex, tlie earlier ones more 

 strongly so. Sculpture of regular, closely set, retractive stria?, as 

 wide as their intervals, every second or third one a little enlarged at 

 the upper end, forming an irregular series of suhsvlural papilla. 

 The la.«t whorl is rounded, or llitre may be an inconspicuous very 

 low cord upon which the stria3 enlarge, defining the base. The 

 aperture is oblique ; peristome scarcely expanding, slightly thickened 

 and white within, the interior elsewhere light brown. Columella 

 vertical, straight, projecting forward a trifle near the insertion, the 

 margin dilated above and adnate, not built forward. 



Length 7.3, diam. above aperture 3.2, including aperture 3.75 

 mm.; whorls 8|. 



Length 7.7, diam. including aperture 3.0 mm.; 9 whorls. 



Length 5.8, diam. including aperture 3.2 mm.; 8 whorls. 



West side of " La Vigia," Trinidad, under stones, etc. Also on 

 the northwest side. 



M. peicmiicus trinidadensis stands near M. avgalosvs ("Gundl.," 

 Pfr.) which it resembles in sculpture and in the structure of the 

 columella, but it differs by the much more obese shape constant in a 

 large number collected, and by the stronger sulural denticulalion. 



'Most of the smnll shells I got nt Znza del Medio were lost through nn nccu 

 dent. These two lots were saved by bciiip in bottles carried in my pockets. 



