Geology and Mineralogy. 325 
Big Horn collection is peculiar among those of Wasatch age, in 
the presence of numerous species of Phenacodus and of new and 
rare species of genera of Coryphodontide. The new Corypho- 
donts here described are Manteodon subquadratus, Hctacodon 
us, U. curvicristis, C. mar- 
ginatus, Metalophodon testis ; and besides these, four previously 
C. simus and C. 
pes, elep ; 
new Artiodactyles, Mioclenus brachystomus and M. etsagicus, 
similar to of Dichobune, even to the presence of the exter- 
nal digits (which are wanting in the Anoplotheriide) ; it differs 
The collections contain two species related to the Lemurs and 
family Prosimiw, named Cynodontomys latidens and Anaptomor- 
hus homunculus. The latter is remarkable for the small size of 
Pp 
the canine teeth. The genus is nearest to Zarsius among the 
Coast Survey triangulation, and elevations will be given by care- 
fully determined contour-lines for every twenty feet. By the aid 
of the maps, it is expected to make out completely the system in 
the distribution of the ore-beds so as to be able to point out where 
they are to be looked for and where not. 
4. Dioptase from Arizona ; by R. C. Hits. (Communicated.) 
—The rare mineral dioptase has been recently found at the Bon 
of mines, near the head of Chase Creek, about nine 
; j by Epo. CLAASSEN. 
(Communicated).—This variety of siderite occurs on hematite In 
he Lak i i 
dral crystals, or more commonly in crystalline crusts. It is often 
also found associated with crystals of calcite, which then form on 
