Ilambach — Revision of the Blastoideae. 45 



5. Genus Mesoblastus, Etheridge fil. and Carpenter. 



Body small, round or elliptical. Base small and flat. Am 

 bulacra narrow and convex, extending the whole length of 

 the body. Ambulacra] integument scroll-like. Deltoids very 

 small, hardly visible in a lateral view, but more so in a sum- 

 mit view, except the posterior one which supports the anal 

 opening, which is outside of the genital openings. Genital 

 openings not confluent, but connected by a small sulcus, run- 

 ning from one to the other in a V shape. Column round. 

 With only one species. 



1. Mesoblastus glaber. Meek and Worthen. St. Louis 

 limestone. 

 Granatocrinus glaber, Meek and Worthen. 



6. Genus Cidaroblastus. 



General form of body elliptical or globose. Ambulacra 

 narrow and linear, extending almost over the whole surface 

 of the body. Central opening never closed except by ambu- 

 lacra] integument. Genital openings ten, constructed by the 

 junction of the deltoid and lancet pieces, very small and never 

 confluent with each other. Anal opening on the posterior 

 side between two of the genital openings. Deltoid pieces 

 very large in all known species, occupying almost half of the 

 interambulacrum. Whole interambulacral space covered with 

 large tubercles for the attachment of spines. Base pieces 

 small and depressed, being never visible in a side view. 

 Column round. This genus contains the typical Granatocrinus 

 of Dr. Troost of which I give three figures on Plate III., 

 drawn from the type specimens in the Troost Collection now 

 in the Smithsonian Institution. Geological position, in the 

 Subcarboniferous rocks. 



1. Cidaroblastus GRANULATus, Eoemer. Subcarboniferous. 



Pentatrematites granulatus, Roemer. 

 Granatocrinus cidariformis , Troost. 

 Granatocrinus globosus, Troost. 

 Orbitremites granulatus, Bather. 



