326 P. HERBERT CARPENTER. 



nothing to do with the arms, as Perrier appears to think, except 

 that both are radially situated. No part of the chambers 

 extends into the arms, the axial cords of which are derived 

 from trunks that start from the interradial angles of the 

 chambered organ. This, however, is a minor point. But 

 Perrier continues to describe how at the level of the chambered 

 organ '' du cordon pedonculaire central, on voit, chez les 

 individus dont les bras sont encore peu developpes, naitre des 

 bourgeons claviformes alternes avec ceux qui, des bras'^ (sic). 

 These are the rudiments of the cirri. " Les cirrhes n'ont done 

 pas de veritable homologie avec les bras; ils naissent du cordon 

 central du pedoncule; les bras, des cinq cordons peripheriques/' 

 In reply to this astonishing statement I would simply remark : 

 (1) The arm-rudiments are in no way derived from the peri- 

 pheral vessels (cordons) of the stem, which expand above into 

 the cavities of the chambered organ ; (2) The cirri are radial, 

 like the arms, and do not alternate with them ; (3) How is the 

 connection effected between the cirri and the " cordon central " 

 of the stem ? The latter is closely surrounded by the " cordons 

 peiipheriques,''^ which represent the five outer vessels in the 

 stem of Pentacrinus (fig. 1), and no extensions proceed 

 outwards from it between the radial (peripheral) vessels, as 

 Perrier's description demands. 



He asserts that the axial organ (= stone-canal of a Star- 

 fish!), which he admits to be the upward continuation of the 

 " cordon central," is " evidernment en rapport avec la nutri- 

 tion des cirrhes." But unless he will further admit that the 

 cirrus-vessels are radial and derived from the cavities of the 

 chambered organ, and also that these cavities themselves 

 pass upwards into the axial organ, I cannot accept his state- 

 ment as at all consistent with the observations of Ludwig and 

 myself. 



He has likewise told us that the upper end of this axial 

 organ in the Peatacrinoid seems to open into the pharynx; but 

 he admits (as well he .may) that further observations will be 

 necessary before he can satisfy himself upon this point. He 

 again ignores Dr. Carpenter's description of its subdivision 



