t 



225 



and outer part of the upper surface distinctly rhorn- 

 boidal, the width from the lateral angles being greater 

 than the height; cell margins very prominent. 



The cells in the centre are not distinctly discernable. 



This small species of the genus has, in a single specimen, 

 a diameter of nearly an inch, with a height of scarcely 

 more than half an inch. It differs from any of those previ- 

 ously known to me, but approaches in character to the R. 

 hemisphericus of the Niagara group of Wisconsin. 



The following species was omitted in the proper place: 



GENUS CHEIROCRINUS (Hall.) • 

 Cheirocrinus stigmatus {Hall.) 



We have evidence of the occurrence of this genus in a 

 species of peculiar character. 



The plates of the body which I have termed the dorso- 

 lateral plates are anchylosed along the dorsal line so closely 

 that no indication of a suture exists, nor is there any visi- 

 ble suture on the ventral side. The lower side of the con- 

 joined dorso-lateral plates is marked by three strong in- 

 dentations, extending from the margin a little way upwards, 

 aud penetrating about two-thirds the thickness of the plate. 

 The articulating surfaces for the three sets of arms are well 

 preserved but the arms are unknown. 



The species differs from any one known to me in the an- 

 chylosed dorso-lateral plates. The surface is marked by fine 

 granules or grandiose undulating striae. 



There are in the collection some othei\remains of Crinoi- 

 dea too imperfect for description, and among them a well 

 marked species of Rhodocrinus-Lyriocrinus, the basal plates 

 <|eing concealed by the column 



