﻿200 Canadian Record of Scieiice. 



FifT. 3, and the whole of the outer declivity or downward 

 slope of the rim is transversely corrugated or ribbed. 



When examined with a lens, the whole surface of 

 the calyx, of the covering plates of the ambulacral grooves 

 and of the small subtriangular plates which alternate 

 with the inner ends of the ambulacral areas at the 

 summit, is seen to be densely pitted or perhaps perforated. 



Two specimens of this species, both collected by Mr. 

 John Stewart in 1886 from the Trenton limestone at 

 Division street, Ottawa, are in the Museum of the 

 Geological Survey of Canada, and an imperfect specimen 

 from the same locality has been kindly lent to the writer 

 by Mr. Walter E. Billings. All three of these specimens, 

 when found, were almost completely covered with a very 

 tenacious shaly limestone, and although they have been 

 both carefully and skilfully cleaned, it is just possible 

 that some of the covering plates of the ambulacral grooves 

 may have been accidentally removed in the cleaning. At 

 present, also, it is not possible to ascertain from either, 

 whether the dense pitting of so large a portion of their 

 surface is caused by "conjugate" pores or not. It is only 

 proper to add that the general outlines of the plates 

 of which the calyx is composed in this species, were first 

 suggested to the writer by Mr. W. R. Billings, who, 

 as is well known, has dev^oted much time to the study of 

 the crinoids and cystideans of the Trenton limestone 

 of the Ottawa valley. 



Astrocystitcs would seem to be most nearly related 

 to Asteroblastios, Eichwald, and is probably referable to the 

 same family, though it clearly differs from that genus 

 in several important particulars. Thus, a comparison of 

 the plates of which the calyx is composed in these 

 two genera shews that, although they have much the 

 same shape and style of sculpture, yet those of Astero- 

 Uastus are both small and very numerous, while those 

 of Astrocijstites are large and comparatively few in 



