MONOGRAPH OF THE EXISTING CRINOIDS. 279 



Ptilametra muHeri. Aglttometra eupedata. 



Cosmiomctra crassicirra. Crossometra helitis. 



Cosmiometra delicata. Perissometra selene. 



Stylometra spinifera. Perissometra patula. 



Stenometra guinquccostata. Perissometra lata. 



Stetwmetra cristata. Pachylometra distincta. 



Stenometra diadema. Chondrometra robusta. 



Daidalometra hana. Calyptom,etra lateralis. 



Parametra orion. Glyptometra tuherosa. 



Parametra granulata. Crinometra insculpta. 



Thalassometra villosa. CMorometra garrettiana. 



f. The outer portions of the sacculi pass to the exterior through large 

 holes near the proximal borders of the side plates. 



Monachometra fragilis. PcBcilovietra sealaris. 



d*. Supplementary side plates are present. 



e*. The supplenient.'iry .side plates are in the form of elongate triangular, some- 

 what recurved, plates situated on the outer distal angle of the side 

 plates, to which they appear to be articulated. 



Thalassometra villosa. 



e'. The supplementary plates are in the form of long boomerang-shaped plates, 

 broader in the outer than in the inner portion, lying in a plane making 

 a relatively small angle with the transverse planes of the pinnule, and 

 situated between the side plates, or just within their distal borders; at 

 the base of the pinnules the supplementary side plates may be divided 

 into a rounded outer and an elongated and less developed inner portion, 

 the former appearing as a supplementary covering plate. 

 Cosmiometra cras.si(Hrra. Parametra granulata. 



Cosmiometra delicata. Oceanometra gigantea. 



Stylometra spinifera. Oceanometra annandalei. 



Parametra orion. 

 c". Plates of both series more or less reduced and often rudimentary, the plates of the 

 two series separated from each other. 

 d'. Plates of one or the other series composed of a delicate reticulation. 



e*. Covering plates composed of a delicate reticulation, or, if more or less 

 spiculiform, lying with the axis parallel to the border of the pinnulars. 

 f . Side plates forming a continuous series, imbricating distally. 

 g\ Side plates dense, with a strong median ridge. 



Pontiometra andersoni. 



g'. Side plates composed of a thin cribriform film. 



Heliometra glacialis. 



f. Side plates not in contact. 



g'. Side plates forming irregular or narrow triangles or bands, with 

 the longer axes at right angles to the pinnulars. 



Tropiometra macrodisous. Beliometra glacialis. 



Tropiometra afra. Pronuichocriniis k»rgr^elensii'. 



Tropiometra carinata. Notocrinus viriti^. 



Thysanometra tenelloides. Isometra i-ivipara. 



142140— 21— Bull. 82 20 



