45 



Family DICHOCRINIDiE. 



TALiAROCRINDS TRIJUGIS, n. Sp. 



Plate III, Fiff. 9, basal view; Fig. 10, summit view; Fig. 11, 

 view opposite the azygous side. 



General form of the cal.yx and vault subelliptical. Calyx glo- 

 bose, truncated below ; plates convex ; sutures depressed ; surface 

 smooth. 



Basals pentagonal and forming a very low cup or disc, one- 

 fourth the height of the calyx, with a subelliptical columnar 

 depression having a small circular facet for the articulating end 

 of the column. First radials large, convex, as wide as high, 

 four are nearly of the same form and rest on straight edges of 

 the basals, while the other one rests in the obtuse angle formed 

 at the union of the two basals, the summit supports two very 

 short, double, second radials, in the middle two-thirds of its 

 width, and one side of an interradial, on each, slightly oblique, 

 superior, lateral edge. There are two double arm openings to 

 the vault over each first radial plate, or one double arm open- 

 ing over each short double second radial. Hence there are 

 four arm openings to each radial or twenty small arms in the 

 species. 



A small, regular interradial rests between the superior lateral 

 sides of the iirst radials and separatee the short second radials 

 and unites with the plates of the vault. The first azygous plate 

 is in line with the first radials, it is larger and longer and ex- 

 tends above the top of the first radials. It supports a range 

 of three plates, as near as can be ascertained from our speci- 

 men, which are followed by plates of about the same size to the 

 azygous opening at the top of the vault. 



The vault is elevated at the arm openings and sharply de- 

 pressed at the interradial spaces. The arm openings are directed 

 obliquely downward. The summit of the vault is convex with 



