Hamhach — Revision of the Blastoideae. 49 



large, occupying nearly f of the whole length. Genital 

 openings constructed by the junction of the deltoid and lancet 

 piece, and not confluent. Poral pieces varying in number ac- 

 cording to the size of the species. Center of the summit closed 

 by additional pieces. The main opening (the anal ?) is lateral 

 and posterior, i. e., the posterior deltoid is divided in half 

 and an elongated piece inserted as a support for the opening. 

 Column round. 



Nearly all the material collected so far is of such a nature 

 as to make a more accurate description impossible. Geologi- 

 cally they belong to the Devonian. Here we And the first 

 irregularity in the construction of the calyx. It is difiicult to 

 sa}^ whether the elongated piece should be counted to the 

 ambulacral or the interambulacral cycle, giving one or the 

 other an old number of pieces. 



The name Nucleocrinus, introduced by Conrad in 1842, is 

 here rejected, first because of its ending in "crinus," and 

 secondly because of the insufficient diagnosis, which reads as 

 follows : " This genus differs from Pentremites sayi in having 

 only one perforation at top, which is central."* On account 

 of this insufficiency it was not adopted by most of our Amer- 

 ican palaeontologists. It is absolutely impossible to recognize 

 or identify a specimen from the above description, accom- 

 panied by an incorrect drawing. 



Roemer's name Elaeacrinus has to be rejected also on 

 account of its ending in "crinus." By so doing, and not to 

 increase the nomenclature with synonyms, I have adopted 

 Lyon's designation as the most suitable one. This genus will 

 include the following species : — 



1. Olivanites angularis, Lj^on. Devonian. 

 Nucleocrinus angularis Etberidge and Carpenter. 

 Elaeacrinus angularis, Shumard. 



*2. Olivanites conradi, Hall. Devonian. 



Nucleocrinus conradi, Hall. 

 Elaeacrinus conradi, Hall. 

 Nucleocrimis verneuili. Hall. 



* Journal of the Academy of Natural Sciences of Philadelphia, 1842, Vol. 

 VIII., page 280, PI. XV., Fig. 17. 



