2 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



mural disk, oval and numerous. Rays or costfe of the under side straight, 

 about twelve at the middle, but bifurcating so as to number near one hun- 

 dred around the periphery, apparently denticulate. Septa few at the center, 

 but increasing by the intercalation of smaller ones between, so as to equal the 

 number of the costre, with which they alternate at the periphery, very finely 

 and sharply denticulate on the upper and lateral edges. 



Breadth, 0.28 inch ; height, 0.12 inch. 



Up to this time, all our knowledge of this little coral has been derived 

 from sections, and impressions of it seen in masses of rock. It is certainly 

 very closely allied to the European M. coronula,to which we had at one time 

 referred it. It seems to differ, however, judging from Edwards and Haime's 

 figures of M. coronula, in having the edges of its septa more finely and more 

 sharply, as well as more regularly, denticulate. This difference, taken in con- 

 nection with its higher geological position, has led me to think it most prob- 

 ably a distinct species. 



This and a small undetermined, turbinate form, of which we have only 

 seen fragments, are the only calcareous corals yet observed in the Cretaceous 

 .rocks of the Upper Missouri country ; and these are both very rare. 



Locality and position. — Moreau River ; from the Fox Hills group, or 

 No. 5 of the Upper Missouri Cretaceous series. 



ALCYONARIA. 



GORGONIIDjE. 



Genus WEBSTERIA, Edwards and Haime. 



Synon. — Websteria, Edwards and Haime (1854), Corals of tbe London Clay, 43. 



Etym. — Dedicated to Mr. Frederic Webster, an English naturalist. 



Type. — TTebsteria crisioides, E. & H. . 



Corallum composite, slender, dichotomous, with straight, flat branches of 

 the same size as the stems, extending out on one plane, and diverging at acute 

 angles from each other; corallites forming little protuberances, oppositely 

 arranged along the edges of the stems and branches in vertical series; calices 

 small, circular, and oblique ; stems and branches with a median line or fur- 

 row along the flat sides, and sometimes splitting longitudinally so as to expose 

 a filiform central axis. 



Breadth of branches about 0.03 inch, and height of corallites a little less. 



The foregoing are substantially the character.-; of this genus given by 

 Edwards and Haime. Although these authors arranged it in the Gorgoniidcv, 



