THE NAUTILUS. 27 



C. pannosum is a species of Little Cayman, south of Cuba, and as 

 none of the Cayman species have been known to occur in the Ba- 

 hamas, it is not unlikely that the identification might be modified 

 on further comparison of good specimens; I think it likely that the 

 form described as C. Pillsburyi is what was identified as pannosum, 

 which it somewhat resembles. C. cinereum of Maynard is the typi- 

 cal C. glans Kiister of New Providence, so that this corresponds with 

 what Dr. Rush collected. 



At all events, it appears that at least six or seven species of land 

 shells inhabit Gun Cay. 





^ 



w 



Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. 



Figs. 1, 2, 3, 4, Cerion Fordii Pilsbry and Vanatta ; Fig. 5, Orion Pills* 

 buryi P. & V., the latter from Gun Cay. 



A NEW SPECIES OF CERES FROM MEXICO. 



BY W. H. BALL. 



Ceres Nelsoni n. sp. 



Shell large, depressed, with a sharp, somewhat upturned keel over 

 which the inner edge of succeeding whorls is laid ; color from pale 

 lemon-yellow to deep orange, the umbilical region polished, translu- 

 cent and always pale lemon-yellow ; whorls seven, the nucleus pol- 

 ished, smooth, translucent, slightly prominent, of a whorl and a half; 

 succeeding whorls flattened above, with an appressed suture, with 

 low, fine raised threads in harmony with the incremental lines tend- 

 ing to break up into granules, which, with the growth of the shell, 

 gradually come to take on a centrifugal direction, and, in the adult, 

 near the aperture, have a trend nearly at right angles to the lines of 

 growth ; on the base the rugosities have a more punctate or vermi- 



