138 THE NAUTILUS. 



HEW H0LLTJ8ES COLLECTED BT MB. A. A. HIITKLET IN BAN LUIB 

 FOTOSI, MEXICO. 



BY H. A. PILSBRT. 



COELOCENTRUM HINKLEYI, n. Sp. 



The shell is shortly rimate, imperforate, the lower third or halt 

 cyliudric, the rest slowly tapering to the truncate summit ; rather 

 Bolid ; brown. Sculpture of backwardly arched narrow ribs, much 

 narrower than their intervals except on the last whorl, where they 

 are more slender and closely crowded. There are about 65 ribs on 

 the penultimate whorl. On some of the later whorls the ribs are some- 

 times weak and rather irregular. The apical breach is closed by a 

 steep, slightly convex plug densely covered with strongly projecting 

 granules. Whorls remaining slightly convex, at least the upper 

 ones have a delicate keel close under the suture ; last whorl rounded 

 basally, having a very weak, inconspicuous, spiral basal cord. Last 

 half whorl straightened, produced forward beyond the preceding 

 whorl. The aperture is oblique, rounded ovate ; peristome obtuse, 

 narrowly recurved. The internal column is moderately large, its 

 diameter contained 3.7 to 4 times in that of the shell. Within each 

 whorl it is rather strongly obliquely swollen, and typically bears a 

 few oblong granules in place of the obliquely vertical laminae of 

 typical species of Coelocentrum. 



Length 35, diam. 8.1 mm.; whorls remaining 12. 



Length 37, diam. 8 mm.; whorls remaining 13. 



Length 35, diam. 8 mm.; whorls remaining 11. 



Length 39, diam. 8 mm.; whorls remaining 14. 



San Luis Potosi : highest Mt. on south side of river at Mecos 

 Falls, and bluff 3 miles north of San Dieguito. 



This is a variable species, represented by many specimens from 

 two localities. In some examples the rather large internal column 

 bears distinct elongated granules ; others have low nodes, while still 

 others have whitish lines which project only slightly from the surface 

 of the column. 



Five specimens of a series from San Dieguito measure : 



Length 46, diam. 8.5 mm.; whorls remaining 18^. 



Length 41, diam. 9 mm.; whorls remaining 12^. 



Length 38.5, diam. 7.7 mm.; whorls remaining 15^. 



