86 Dr. P. H. Carpenter on the 



are really compound joints, consisting respectively of the 

 original second and third radials or first and second distichals, 

 united by syzygy. So far as the radials are concerned, Wal- 

 ther himself suggests as a possibility * that the axillary should 

 be regarded as " verschmolzenes Radiale II. + Radiale 111." 

 Quenstedt's observations on the axillaries of 8. costatus show 

 that the line of syzygy, which is so plain in some specimens, 

 may disappear altogether in others f ; and it is therefore 

 quite possible that it may have disappeared in Walther's 

 S. gracilis. I should not like to speak with certainty as to 

 the presence of syzygies in the arms of this specimen, but 

 there are certain indications in both the figures which Walther 

 gives of it which lead me to think that syzygies are not so 

 entirely absent as he asserts ; while his " Schema des Arm- 

 baues " of a varietal specimen |, which I have copied (fig. 2, B) 

 shows, in what seems to me the clearest possible manner, 

 that the third brachial is a syzygial joint in one arm, and that 

 another has been broken at a syzygy in the second brachial, 

 so that the hypozygal only remains. 



We now come to Solanocrinus imperialis. According to 

 Walther's figures and description of this unique specimen §, 

 the second radials are the axillaries. Now it is a very 

 general rule among those Neocrinoids in which the rays 

 divide that there are three radials in the calyx. This holds 

 good in the Encrinidse, Apiocrinidge, Pentacrinus^ Bathycrinus, 

 and for all the recent Comatulae, though there are a very few 

 fossil species of Aritedon in which the second radial is undoubt- 

 edly axillary, a fact for the knowledge of which I am indebted 

 to the kindness of M. de Loriol. 



The possibility of the large radial axillaries of Solano- 

 crinus imperialis being compound joints does not seem to 

 have occurred to Walther, as it did in the case of S. gracilis. 

 To my mind, however, this is by no means an improbable 

 supposition, for the characters of the axillaries are such as I 

 have never met with in recent Comatulas unless they are 

 syzygial joints. They are very suggestive of the compound 

 axillaries in the group of species represented by Actinometra 

 Solaris ^vA its allies, and also closely resemble those oi Actin- 

 ometra ])aucicirr a ^ which are shown in fig. 1,A. In this 

 latter type the distichal series consists of two joints united by 

 syzygy, and there is a similar union between the first two 

 brachials. I cannot avoid the suspicion that this is likewise 



* Op. cit. p. 174. 



t Encriniden, Tab. 96. fig. 43, p. 175. 



X Op. cit. Taf. xxvi. fig. 4. 



§ Op. cit. pp. 168-171, Taf. xxv. fig. 3, Taf. xxvi. fig. 6. 



