﻿72 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



[vol. 47 



on the relative amount of material deposited at the intersections or 

 throughout the length of the ridges, and also upon the strength of 

 the sutural depressions. The specimens studied form a series con- 

 necting the extreme types of ornament by insensible gradations. 



The arrangement of the calyx plates is shown in the accompany- 

 ing diagram, fig. 5. 



Arms fifteen, three to the ray. The arm bases are large, and the 

 openings are directed obliquely upward. Interradial pores three, with 

 one or two between adjacent brachia. 



Tegmen slightly elevated, composed of thick, rugose plates with 

 deeply sunken suture lines. The anal tube is nearly central in 

 position. 



Column small, circular, with pentalobate canal. 



Remarks. — This species somewhat resembles the preceding in sur- 

 face ornament, but differs from it in size, in the number of arms and 



Co* 





o l 



($$c0 



Fig. 6. — Plates of an abnormal individ- 

 ual of Dolatocrinus asterias n. sp. 





Fig. 7. — Plates of an abnormal individ- 

 ual of Dolatocrinus asterias n. sp. 



respiratory pores, and in the direction of the arms as they leave the 

 body. The basal depression is deeper, narrower, and more definitely 

 outlined. The tegmen of this species differs widely from that of 

 Dolatocrinus costatus n. sp., both in its more convex form and in its 

 small, elevated, and rugose plates. 



An nmg those referred to this species are two incomplete specimens 

 which are abnormal in the number of their calyx plates. The speci- 

 men from which fig. 6 was drawn retains the characteristic surface 

 ornament of D. asterias n. sp., and differs from the type only in the 

 absence of one costal, as represented in the diagram. A young speci- 

 men also showing the characteristic form and ornament of this 

 species is unique in possessing six plates in the radial series. The 



