COMATTJLJE OF THE MERGTJI AECIIIPELAGO. 309 



of Antedon, as I have pointed out elsewhere*; and the ouly 

 character, therefore, on which he can possibly rely for the 

 separation of Solanocrinus from Antedon is the presence 

 of syzygies in the arms of the latter and their absence in 

 those of the former genus. But the material on which he has 

 founded this generalization seems to me to be altogether insuffi- 

 cient. Few, if any, of his very limited number of specimens have 

 as many as forty arm-joints remaining, and these are rarely in 

 a satisfactory state of preservation ; so that it is somewhat rash 

 to speak positively about the total absence of syzygies in the 

 arms of Solanocrinus. In fact, I have shown reason to believe 

 that syzygies are present even in some of the arms which are 

 figured and described by "Walther as being entirely devoid of 

 them. 



On the other hand, Antedon Andersoni is remarkable for the 

 rarity of the syzygies in the arms. It was a long time before 1 

 could discover any at all, except that in the third brachial. In 

 fact, I did not succeed in finding any in some arms ; while in 

 others they are often separated by intervals of ten or a dozen 

 joints. In A. elegans and A. multiradiata the second syzygy 

 may not be till the fortieth or even the sixtieth brachial, and the 

 intervals between its successors may be fifteen or twenty joints. 

 Were these species in the fossil state, therefore, with only the 

 lowest portions of the arms preserved, and that but badly, it 

 would be easy to overlook the syzygy in the third brachial, and 

 to infer that none were present in the arms at all ; though such 

 an inference would not be in accordance with the facts of the 

 case. I cannot but suspect, therefore, that "Walther's attempt to 

 establish the absence of syzygies as a diagnostic character of 

 Solanocrinus is due partly to a generalization on imperfect material, 

 and partly to an insufficient acquaintance with the variations in 

 the distribution of the syzygies among recent ComatulaB. 



Any member of the Megans-group, preserved in the fossil 

 state, would make a fairly good Solanocrinus ; for each species 

 has a relatively large centro-dorsal, bearing a good number of 

 cirri, with few syzygies between the brachials, but one between 

 the two outer radials. This latter condition certainly occurs in 

 Solanocrinus costatus, and probably also in S. imperialis and 



* " The Generic Position of Solanocrinus" Ann. & Mag. Nat. Hist. 1887, 

 ser. 5, vol. xix. pp. 82, 83. 



