Prof. C. Semper on the Anatomy o/ Comatula. 205 



The question now is, Where are we to look for the nervous 

 system ? In regard to this, unfortunately, my examination 

 has conducted to no conclusion, because I have not yet had 

 any opportunity to repeat it on living animals. It might even 

 be possible that the cord (n) in the interior of the calcareous 

 skeleton, which has hitherto always been regarded as a vessel, 

 is a nervous cord ; and if so, then the so-called heart situated in 

 the calyx would certainly have to be looked upon as a ganglion. 

 That it is not a vessel, is shown by the total absence of a 

 lumen ; its mass consists of very fine close-lying fibres, which 

 Hoffmann also, in his recently published work, compares to 

 nervous fibres. On the other hand, above the tentacle-canal 

 there is a second fibrous cord, which was first discovered by 

 Perrier (Archives de Zoologie Experimentale, tome ii. 1873, 

 p. 55, pi. iii. f. 8, m), and which I have also recognized in 

 sections of the arm of Comatula which I have preserved for 

 some years (see x, fig. 1). This cord also appears probably 

 to belong to the nervous system. Yet in no case is proof 

 furnished of the nervous nature of either the one or the 

 other ; the only thing fully established with respect to the 

 first, is the absence of any ground for interpreting it as a 

 vessel. 



In conclusion, I wish to add a remark on the work of Perrier 

 above referred to. He strenuously contends that one of the 

 two canals described by Muller in Pentacrinus, and by Car- 

 penter in Comatula, is not present, viz. that named by the 

 latter " canalis coeliacus." But in this he to a certain extent 

 contradicts himself. At pp. 48, 49, in directly contesting the 

 presence of the lower canal of the arm, he says : — " for there 

 (in adult individuals) the tentacular canal appears always to 

 rest directly upon the thin layer of tissues which invests the 

 skeleton, and in that layer nothing resembling a canal can be 

 distinguished." In the same page, however, he says " it is 

 upon the walls of the prolongations of the general cavity into 

 the pinnules that the genital glands are developed;" further, 

 p. 57, " the tentacular vessel is seen to rest directly upon the 

 membrane that envelops the calcareous axis ;" and, in the same 

 page, " immediately above this covering " (of the calcareous 

 axis) " is the general cavity." A more distinct contradiction 

 cannot be imagined. It seems to me that Perrier has been 

 misled by the German word Gefass. He calls the tentacle- 

 canal a canal, because he wishes to indicate thereby its be- 

 longing to a system of vessels distinctly cut off from the body- 

 cavity ; while he will not give that name to the canal-like 

 prolongations of the body-cavity (which he yet himself 



Ann. & Mag. N. Hist. Ser. 4. Vol. xvi. 15 



