116 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. X.X.XI. 



The specimens measure: 



Measurements of Coelocentrum nelsoni. 



« Type. 



6 The last four. 



CCELOCENTRUM PFEFFERI Dall. 



There are four specimens and two fragments of this species in the 

 collection, Cjat. No. 107367, U.S.N. M., all from Ocozoouantla, Chiapas, 

 Mexico. 



Measurements of Cwlocentrum pfefferri. 



Number of 

 whorls. 



"8.5 



8.1 

 8.6 



7.8 



Length. 



vim. 

 43.1 

 44.5 

 42.7 



38.7 



Diameter 

 of penulti- 

 mate 

 whorl. 



mm. 

 15.8 

 15.7 

 15.5 

 15.4 



"Type. 



CCELOCENTRUM PITTIERI, new species. 



Plate III, fig. 7. 



Shell elongate conic, turrited, with truncated summit, light brown 

 on the spire, and whitish on the base. The shell attains its greatest 

 diameter in the fourth to last whorl, from which it tapers gradually 

 to the ninth to last; the four whorls preceding this are of almost 

 the same caliber. Plug evenly and minutely granulose. Puncture 

 round, small. Whorls moderatel}^ rounded, marked by many quite 

 regular, veiy narrow and acute, obliquely backward slanting riblets, 

 whicli are less than half as wide as the spaces between them. These 

 riblets are best developed on the posterior half of the spire; on the 

 anterior half they are less regular, less acute, and much more distantly 

 spaced. On the tifth to last whorl I counted 8 riblets to a space of 2 

 mm., while on the penultimate whorl only half that number were 

 present. The spaces between the riblets and the sides of the riblets 

 displa}' a tine crinkling, which almost amounts to closely spaced spiral 

 markings. Sutures well marked. Periphery of the last whorl marked 

 by a small thread-like angulation; the space immediately anterior to 



