REPORT ON THE CRINOIDEA. 



259 



the cirrus-joints to be also unprovided with definite spines, though they have the same 

 sharply carinate appearance as those of Antedon irregularis. 



The first radials of these individuals are also mostly concealed, as is the case in 

 Antedon irregularis, though in the type of Antedon decipiens from the Arafura Sea 

 they are "quite distinct" as described and figured by Bell; 1 but they are much less 

 distinct in the white individuals from Prince of Wales Channel. In all the specimens 

 from this latter locality, therefore, the first radials resemble those of Antedon irregularis 

 rather than the radials of Antedon decipiens; but some of them had spiny cirri as in 

 the type of Antedon decipiens, while in the others the joints are only sharply carinate 

 as in Antedon irregidaris. The arms and pinnules of all these specimens, however, are 

 most like those of Antedon decipiens. 



It would seem impossible, therefore, to make any distinction between the two species 

 in the characters of either the arms, the radials, or the cirri ; and this conclusion is 

 confirmed by the following considerations. The two individuals from the Arrou Islands, 

 which I formerly referred to a new species, Antedon dubia, have about thirty-five cirrus- 

 joints, with the later ones carinate as in Antedon irregularis (PL XXXVI. fig. 1 ; 

 PL XLIX. fig. 1). But they have relatively large and conspicuous first radials with a 

 sculptured surface (PL XXXVI. fig. 1), exactly as in Bell's figured specimen of Antedon 

 decipiens, which, like these, has no palmars. The arm-bases of the smaller individual 

 from the Arrou Islands resemble those of Antedon decipiens, while those of the larger 

 one show more of the characters of Antedon irregidaris. On the other hand, Antedon 

 variipinna and Antedon crenulata both have palmar series and thirty or more spiny 

 cirrus-joints, while the first radials are fairly distinct, those of Antedon crenulata being 

 more or less sculptured. Neither species has specially rounded arm-bases, like those of 

 Antedon irregularis, though the general outline of the joints is the same in all the 

 types. 



The variations in the characters of all these different forms may be conveniently 

 expressed by letters as follows : — 



1 " Alert " Report, pi. xi. fig. b. 



