102 Dr. P. H. Carpenter on some Points in 



technique. Under these circumstances he has certainly seen 

 much which had escaped mj notice. But this scarcely justifies 

 him in saying " Toute la physiologic des crinoides demeure 

 done, apr^s le travail du naturaliste du Challenger, dans 

 I'obscurit^ oti il I'avait trouv^e" *. I freely admit that I 

 have not yet risen to the conception that the water which 

 enters the body-cavity of a Crinoid by the ciliated funnels of 

 the disc is expelled by powerful muscles through pores at the 

 syzygies of the skeleton ; nor that the blood- and water- vessels 

 of a Crinoid, together with the body- cavity and its radiating 

 extensions, constitute a vast system of intercommunicating 

 canals with " le meme role physiologique que I'ensemble 

 des cavit^s creusees dans le corps des polypes et des 

 dponges " t- 



It is difficult to study pure physiology upon spirit speci- 

 mens, and it is unfortunately true that 1 have been unable to 

 add much to Ludwig's account of the circulatory apparatus ; 

 but, all the same, J. venture to think that I have made some 

 additions to our knowledge of the physiological anatomy of 

 the Crinoids. I speak under correction ; but it is certainly 

 my impression that the lieport on the ' Challenger ' Crinoids, 

 together with my previous writings upon the subject, contains 

 the first descriptions and figures of the following points of 

 physiological anatomy : — 



1. The trifascial articulation between certain joints of the 

 rays and arms of Bathycrinus, and the entire absence of 

 syzygies in this genus. 



2. The complex coiling of the alimentary canal in Actino- 

 metra, and the accompanying variation in the structure of its 

 ovoid gland, to use Perrier's own expression. 



o. The presence at the sides of the ambulacra, both of disc 

 and arms, of radiating branches from the axial nerves of the 

 skeleton ; and the extension of fibres from this network into 

 the spinelets on the disc of Pentacrmus. 



4. The ramification within the stem-segments of fibres from 

 their central nervous axis. 



5. The absence of any ambulacral grooves and of their 

 associated organs on the arms and disc in many specimens of 

 Actinometra, and on the completely plated genital pinnules 

 of some species of Antedon. 



6. The presence of well-developed ovaries in the disc of 

 individuals of two species of Antedon and' one of Actino- 

 metra \. 



* Loc. tit. p. 693. t Ibid- p. 692. 



X Professor Perrier iutimatestbat I difter from ni}- father with respect 

 to that portion of the genital glands which lies within the disc of a 



