Te7'7nf; ?'?? Crinoid Morphology, /^O 



free from tlic vadials upward. Let us now consider it with 

 rctereiicc to pinnulatc anus. 



First in cases where these are free. Strictly speaking tlie 

 first ossicle that bears a pinnule is homologous with tlie prim- 

 axil, and the next one bearing a pinnule with the secundaxil. 

 But however philosophical this may be, it is clear that, after 

 all, practical peoj)le do need some name that shall include all 

 the jiinnuliferous ossicles of any one series or order. In 

 supi)lying this want we may adopt one of two courses. Either 

 we may retain the present system with its illogical names, or 

 we may evolve a new system that shall answer the require- 

 ments of a morphological terminology as laid down on 

 p. 55. There can be little doubt that the former course will 

 recommend itself to those who have to deal only with recent 

 Crinoids, the vast majority of which belong to the genera 

 Antedon and Actinometra {Comaster), for the species of which 

 genera formula3 have been constructed by F. J. Bell * and 

 P. H. Carpenter!. When, however, we consider fossil 

 pinnulate genera, especially in the Camerata, the second 

 course would appear to be accompanied by fewer difficulties. 



For descriptive purposes, then, I would propose a termin- 

 ology congruous with the j\Iullerian term " distichals." The 

 objections to this that were stated above do not apply in the 

 case of pinnulate genera, for in them the branching is almost 

 always quite regular and does not take place so many times : 

 except in formulae, it would rarely be necessary to speak of 

 any brachials higher than the octastichals. As a rule the 

 monostichals correspond to the primibrachs, and there is no 

 reason why the latter terra should not be employed. In 

 Metacrinus and Calamocrinus^ however, pinnules are borne by 

 the brachials of the first order. In that case the two terms 

 do not apply to the same things, and the word "monostichals" 

 must be adopted. 



In cases where some of the proximal series of brachials 

 enter into the dorsal cup, these may be called by Wachsmuth 

 and Springer's term " Fixed brachials " or " hracliiaUa Jixa ; " 

 while those outside the limits of the cup will be " Free 

 brachials " or '^ brack iah'a Jiberay In formula and symbols 

 it would have been natural to have expressed the difference 

 between the two by enclosing the fixed brachials in brackets. 

 Brackets, however, have already been employed by Bell and 

 Carpenter, with far less obvious significance, to denote uncer- 



* " An attempt to apply a method of Formulation to the species of 

 the Comatulidfe &C.,' Proc. Zool. 8oc. Loud. 1882, pp. o30-o36. 



t ' Challenger ' Zoology, vol. xxvi. part Ix., Report on the Comatulpe, 

 pp. 4 i et sqq., 1888. 



