INTRODUCTION. 



43 



papill.ij, the covering plates of the arm are reduced to 

 granules. 



Gregory, in order to establish a uniformity in nomenclature, founded a new 

 Order, the Lysophiurae, to contain the forms included by Stiirtz in the Ophio- 

 Encrinasterias. The remaining genera were placed in the Streptophiurge, which 

 was regarded by Bell as containing more primitive forms than those of the 

 Zygophiurse. 



The same objections that have been urged against the views of Stiirtz apply 

 with even greater force against the classification proposed by Gregory. Investiga- 

 tion shows that there is a wide difference between the structure of the Palaeozoic 

 " Ophiuroidea " and that described for Recent Streptophiurae. Indeed the recent 

 work of Miss Sollas throws considerable doubt on the so-called " streptophiuran " 

 structure, and it appears to me that the Streptophiurge may be, not more primitive 

 than the Zygophiuras, but secondarily degenerate. 



Classification of the Fidseozoic Ophiuroidea, as arraiujed hij Stiirt:: in 3 899 to 

 sJioir the correspondence of his earlier classifi cation n-ith tliat of Greyorij. 



Stlrtz, 1893. Gregory, 1896. 



Sub-order Ophiure.e. 



OPHIUROIDEA. 



1. Family Oplno-Encriuasterise, Stiirtz, 188(3, 

 1890, 1893. 



With live arms, disc round or pentagonal. 

 Without dorsal, radial, ventral and mouth- 

 sliields. Two halves of the vertebrse not fused, 

 placed alternately with each other. 



1. Order LYSOPHIUR^. 



Ophiuroidea in which the ambulacral ossicles 

 are alternate and are not united into vertebral 

 ossicles, but those of each segment are separate. 

 There are no ventral arm-plates, and the ventral 

 side of the arm is occupied by an ambulacral 

 furrow. 



Protaster sedgwicki, Forbes. 

 Protasfer forhesi. Hall. 

 Not investigated. 

 Bumleiibacliia benecke!, Stiirtz. 



1. Family Protasteridse. 



Lysophiurse with boot-shaped ambulacral 

 ossicles, each composed of a " body " in the 

 median line of the arm and a lateral " wing " at 

 right angles to it. 



Protaster- sedgivicki, Forbes. 



Not investigated. 



Protaster hiforis, Gregory. 



Bundenbachia beneckei, Stiirtz. 



Protaster brishujoides, Gregory. 

 Protaster leptosoma, Salter. 



2. Family Palseopliiurida). 



Lysophiurse in which the ambulacral ossicles 

 consist of a bar-shaped or sub-graduate " body " 

 without wings. 



Sfurtzura brlsinyoides, Gregory. 



Sturtzura leptosoina, Salter. 



