﻿404 DESCRIPTIONS OF NEW SPECIES OF 



HETEROCRISINA, n. g., Gabb and Horn. 



Colony dendroid, fixed at its base, from which slightly flattened branches arise, 

 dichotomous ; branches provided with cells on their upper surface ; cells oval, having 

 their long diameter directed alternately to the opposite sides of the branch ; laterally 

 the cells are arranged in rows with flutings from one row of cells to the other : below, 

 branches irregularly striate. The increase takes place only by additions to the ex- 

 tremity. 



This genus occupies an intermediate place between Filicrisina and Bicrisina, the 

 former having one row of cells on the upper surface, the latter two, while Hetero- 

 crisina, from the peculiar arrangement of the cells on the upper surface, appears to 

 occupy a transitionary place between the one and two-rowed Grisinidce. 



H. Abbottii, G. and H. PI. 69, figs. 45, 47. Colony formed of slender branches, 

 slightly compressed ; cells oval, edge rounded, slightly elevated, with a fine groove 

 bounding the cell ; lateral cells irregularly oval. 



Locality. — -With the above. My collection ; from Mr. Abbott. 



