20 Dr. P. H. Carpenter on the 



disting-uishes it accordingly as the " Brachianal." He states 

 that " in size and position it is just like the adjacent arm- 

 plate " *. But is this really the case ? Is there the same 

 articulation between its under surface and the bifurcating 

 piece below it as between the latter and the arm-plate of the 

 right posterior ray ? This has yet to be demonstrated ; and 

 until such a demonstration has been given the term "axillary" 

 should not be applied to the bifurcating piece, as has been 

 done by Bather. Whatever be the merits of his theory, as 

 applied to other Fistulata, there appear to me to be grave 

 doubts respecting the correctness of his interpretation of the 

 plate X in locrinus. This is regarded by Wachsmuth and 

 Springer as the first plate of the anal tube, and not in any 

 way as a '' special anal,'" or brachianal as Bather calls it ; and 

 if such be the case, the bifurcating piece on which it rests is 

 not in any sense an axillary. Bather, however, not only calls 

 it an axillary plate himself, but also represents the American 

 authors and myself as having done the same, which is not 

 the case. I did not state " that Waclismuth and Springer 

 homologize the lower half of the compound radial in Dendro- 

 crinus with the upper axillary plate in locrinus.'''' Neither 

 did the American authors misquote me " as having suggested 

 that the axillary plate of locrinus was an ' azygos ' plate " '\. 

 Neither they nor 1 used the term " axillary " at all, so that 

 there was no reason for Bather to represent us as having 

 done so, more especially as we do not yet know that the plate 

 in question is entitled to this name. 



6. Interambulacrals and Adamhulacrals. 



In Miiller's classical memoir, " Ueber den Bau der Echi- 

 nodermen," after discussing the views of de Blainville and 

 A. Agassiz respecting the interambulacral plates of a Star- 

 fish J, he proposed to distinguish the marginal plates of the 

 ambulacra from the remaining interambulacral plates by the 

 name " adambulacral." Those plates situated between the 

 ambulacra on the ventral surface of the body, which are so 

 well developed in the pentagonal forms, were called inter- 

 mediary interambulacral plates ; and in a third category he 

 placed the lower marginal plates of the rays. The term 

 adambulacral proved to be a very convenient one^ and it soon 

 found its way into the current nomenclature both of zoology 

 and of pala3ontology. It was not, however, adopted by A. 



* Ibid p. 330. t Ibid. pp. 321, 322. 



\ Abhandl. d. Berlin. Akarl. Jahrg. 1803 (1854), pp. lOl, 1(52. 



