1898] WACHSMUTH AND SPRINGER ON CRINOIDS 343 



pinnulate Impinnata and the pinuulate Pinnata, two sub-orders 

 between which no connecting links are known, they force one to 

 demand the evidence that the latter are not derived independently 

 from pinnulate Inadunata. If they will not admit the origin of 

 pinnules from armlets, it is hard to see how they can maintain the 

 descent of Pinnata from Impinnata. It must be remembered that 

 the only essential diflerence between the Pentacrinidae (the type of 

 Johannes M tiller's Articulata) and the Articulata Pinnata of Wachs- 

 muth and Springer, lies in the possession of a proximale by the latter. 

 Now, why can this not have been acquired just as easily as pinnules ? 

 It was acquired once, we may suppose, when the Impinnata originated; 

 why not a second time, when the Pinnata separated off ? This 

 question has not been discussed by Wachsmuth and Springer, 

 although necessitated by their opinions far more than by mine. 



As for the name ' Articulata ' our authors themselves recognise 

 that it may be objected to on the ground that it does not correspond 

 with the Articulata of Mliller, and they propose the name ' Articulosa ' 

 as an alternative. That name, however, had already been used by 

 Dr Jaekel in a different sense, in 1894, and the very appropriate 

 name Flexibilia was proposed by Professor K. von Zittel in 1895. 

 This last, being free from confusion with other names, is the best 

 to adopt. 



Let us turn now to the Order Inadunata. These " represent 

 the simplest form, their dorsal cup being composed invariably of 

 only two rings of plates, or three when infrabasals are present. It 

 has no supplementary plates, except an anal piece ; but this is not 

 represented in all of them. The arms are free from the radials up." 

 This order is divided according to the structure of the tegmen into 

 two sub-orders : the Larviformia, in which the tegmen consists only 

 of five orals, completely covering the mouth; and the Pistulata, in 

 which the posterior inter-radius is " drawn out into a sac or tube." 

 Long ago I criticised this division. Now, in the first place, I repeat 

 that it does not hold good on mere morphological grounds ; the anal 

 tubes of Symhathocrinus and Pisocrinus are quite as highly developed 

 as that of Her-petocrinus. The presence of a tube in the last-men- 

 tioned genus or in Heterocrinus is no more proof of the presence of 

 interambulacrals in the tegmen than it is in Pisocrinus. But as I 

 do not wish to plough barren fields of controversy, I leave this for 

 the more important consideration that, even if our authors' statement 

 of fact be granted, it appears to be admitted by them that the struc- 

 ture of the Larviformia represents a primitive stage, and that from 

 them the Fistulata descended. Dr Jaekel has shown, for instance, 

 that Mycocrinus and CatiUocrinus are final stages in a series of 

 which Pisocrinus and Calycanthocrinus are the earlier terms. The 

 former are ' Fistulata,' the latter are ' Larviformia.' I have my- 



