VOLBORTH ON CYSTIDEA. 17 



M. von Buch's opinion, that the singular orifice alluded to on the 

 cup of the Sphaeronites is sexual, may be admitted the more readily, 

 since in other Echinoderms the sexual orifice always has a position 

 having reference to radiated structure, and that the arms on which, 

 in the existing Crinoids, the sexual organs are carried, have not yet 

 been perceived. But there is no proof of this : we find in none of 

 the other Echinoderms any analogy with such singularly-formed 

 organs, and there can be no absolute proof of such view in the case 

 of animals which lived so many ages ago. Nor need we wonder at 

 this, if we consider in how many points where the living animal is 

 exposed to our investigation, there is still much obscurity. I need 

 only refer, with regard to the Echinoderms, to the madrepore plates 

 and the pedicellaria. 



Since then the use of this orifice is not yet ascertained with cer- 

 tainty, is it reasonable, that on account of an hypothesis, were it ever 

 so probable, a distinctly obs:erved fact should be denied, even if it 

 should turn out that there are no arms at the hypothetical ovarial 

 orifice ? 



The conclusion, with regard to the armless condition of these ani- 

 mals, seems in the last place unreasonable, since an ovarial orifice on 

 the cup is by no means inconsistent with the existence of arms. Is 

 it the case, it may be asked, that the arms of the Comatula are only 

 sexual organs ? or rather, is not this function merely accessory, and 

 are not the arms more especially organs of touch and prehension, 

 obtaining food for the animal ? Our knowledge, both physiological 

 and anatomical, of existing Crinoids is almost entirely drawn from 

 the Comatula, but who will assert that the numerous and varied 

 forms of this family in the ancient world were all distinctly modeled 

 after the same law ? Even in the Astoria the ovaria are situated 

 sometimes at the place where the amis are given off, sometimes in the 

 arms themselves* ; and in Comatula the sexual organs are developed 

 in pennules which have not hitherto been shown to correspond with 

 the arms of Cystidea. There is therefore no sufficient reason for 

 assuming that in the case of the latter group there might not have 

 been a special ovarial orifice not in the vicinity of the arms. The 

 warmth with which M. von Buch has declared that arms do not 

 exist, seems the more extraordinary when it is remembered that he 

 it was who fi'rst asserted the possession of arms in the Cystidea. In 

 his work on the formations of Russia f, he says, "the plates which 

 on the summit of the upper part of the cup (in Hemicosmites) cover 

 the mouth, appear to run out into three little probosces or arms, 

 which are hollow, and which may probably be three orifices of the 

 mouth."- More recently however he recalls this view, and says J, 

 " it appears as if the proboscis was separated into three parts which 

 must have been surrounded with small plates, since they do not re- 

 mind one in the least of arms." Many beautiful specimens in my 



* Miiller, Pentacrinus, p. 62. 



f Beitr. zur Best, der Gebirgsform. in Russl. (1840, p. 35). 

 J Cystideen, p. 20, Transl. I c. pp. 33, 34. 

 VOL. III. PART II. C 



