phylum ECHINODERMATA. 



Glass CRINOIDEA. 



Caliculate, actinogonidial, statozoic Echinodermata, provided with branching articulated 



arms, and without »hydrospires». 



This definition is a sliglit modification of that recently proposed by my colleague 

 Prof. F. Jeffrey Bell in his paper on the Arrangement and Inter-relations of the Classes 

 of the Echinodermata. *) Bells definition did not exclude certain brachiate Cystidea, e. g. 

 Porocrinus and Caryocrinus, which can only be excluded on the assumption that the 

 hydrospires» or »hydrophores» have sonie distinct morphological and physiological im- 

 portance. Since that assumption is at present generally admitted, it is advisable to give 

 expression to it in onr definitions; but it is by no means itnprobable that it will have to 

 be eitlier discarded or modified at no distant date. Discussion of this point is not, how- 

 ever, of pressing importance owing to the absence from Gotland of any Cystidea that could 

 legitimately be considered as brachiate and actinogonidial. 



( )rder INADUNÅTA. 



Crinoidea in which all brachials are frce; and in which no interradials enter the 

 dorsal cup, nnless il be in the posterior interradius. 



This naine and this Order are retained provisionally, although it seems impossible to 

 draw up any diagnosia that, while applying to all Inadimata, shall exclude such Camerata 

 as Platycrinus or such Articulata as Cyrtidocrinus and Pycnosaccus. This, however, may 

 be due to the fact that the other Orders of Crinoidea have been derived from this one, 

 and that such genera as those above-mentioned represent stages in the evolution not far 

 removed from the true Inadunate type. The still greater difhculty, that presents itself when 

 one attempts to distinguish the Crotalocrinida> from the Inadimata, is probably due to a 

 simpler reason. For the present, however, it is convenient to treat of the Inadunata as 

 they have been understood by Wachsmuth and Spkixgeu and by P. II. Cakpentek. 2 ) 



') Ami. Mag. Xat. Rist. ser. G, vol. VIII, pp. 206—215, Sept. 1891. 



'-) The last classification of the Crinoidea puhlislud liy Dr. Carpenter appeared in Nieholson and Lyddekers 

 ►Palaeontologv . ed. 1H89. pp. 445 — 0. This, however, was merely a stop-gap uliieh its anthor was prepared to 

 niodify in inanv points. 



