Generic Position o/Solanocrinus. 



85 



to me to prove most conclusively that the arms of Solano- 

 crinus costatus are not so entirely devoid of syzygies as he 

 asserts. On Taf. xxvi. fig. 11, he gives a "Schema des 

 Armbaues von 8. costatus, mit ergiinzten Pinnulis," a part 

 of which 1 have copied in fig. 2, A. The first pinnule is 

 represented on the left side of the fifth brachial, and five 

 others follow in succession, alternating on opposite sides of 

 the arm till the tenth joint. But there is no pinnule at all 

 upon the broad side of the eleventh joint, which is continuous 

 with that of the twelfth, and this bears a pinnule which is on 

 the opposite side of the arm to that on the tenth joint. If 

 this arrangement be not due to a malformation, which I see 

 no reason to believe, it has only one possible explanation. 

 The eleventh and twelfth joints are united by syzygy, and 

 the eleventh, as is invariably the case with the hypozygal, 

 bears no pinnule. So far as my experience goes, there is no 

 other possible way of accounting for the absence of a pinnule 

 on this joint ; and, if Walther's restoration of the arm is justi- 

 fied by the condition of the specimen, I have no hesitation 

 whatever in saying that there must be a syzygial union be- 

 tween this pinnule-less joint and its successor. I think that 

 this will be evident to any one who will compare the copy 

 of Walther's figure (fig. 2, A) with that showing the syzygies 

 in the arm of Antedon rosacea (fig. 3, C). 



Fig. 3. 



Fig. 3. — Syzygies in the arm of Antedon rosacea. A, epizygal ; B, hypo- 

 zygal ; C, dorsal aspect of an arm-fragment, showing the syzygial 

 unions and the alternation of the long sides of the arm-joints : x 4. 



Let US now turn to his description of the type form of 

 Solanocrinus gracilis. I have little doubt, for reasons which 

 I shall presently explain, that the pentagonal and relatively 

 long axillaries of this individual, both radial and distichal, 



