72 PROCEEDINGS OF THE ACADEMY OF [1890. 



whorls are distiuot. This is the largest aj^)Ox of the Tribulus or 

 typical Mnrex gn.>up. 



The present species ditiers wholly fn.>iu all the other members of 

 this group in having two and one-halt' whorls instead of one as in 

 those hitherto described. The whorls are of a glassy texture, a feat- 

 ure not possessed by the other members of the group. 





