406 THE VOYAGE OF H.M.S. CHALLENGEE. 



following passage :^ — " Ainsi le plus grande uombre des entonnoirs cilies, Vorgane 

 spongieux, Vorgane axial, les chambres de Vorgane cloisonne, ne forment qu'iin seul et 

 meme systeme, a la fois I'analogue et I'liomologue du systeme formd chez les Oursins, 

 les Asteries et les Ophiures par la lylaque madreporique, le canal hydrophore ou canal 

 du sable et la glande ovoide qui lui est constamment annexee." 



The above statement harmonises admirably with the theory which Perrier has so long 

 l)een advocating respecting the fundamental unity of what are generally kno\\Ti as the 

 water-vascular and the blood-vascular systems of Echinoderms. This theory is by no 

 means new, and appeared to receive confirmation from the results of Perrier's study of 

 the circulatory apparatus of the Urchins.^ But Koehler's later observations on the same 

 subject ^ have shown that several important points in the anatomy of the vascular 

 sj^stem of an Urchin entirely escaped Perrier's notice. Although he adopts Perrier's 

 views, his observations are capable of an altogether different interpretation, as I have 

 shown elsewhere ;* while they afford a strong confirmation to Ludwig's description of the 

 vascular system of the Asterids.' This was founded upon the most careful and elaborate 

 observations which have yet been published ; and although their correctness has been 

 called in question by Messrs. Perrier and Poirier,* none of the French zoologists have 

 published a single figure in proof of their assertion that what is generally called the blood- 

 vascular system of a Starfish communicates with the exterior through the madreporite. 



As regards both Starfishes and Urchins therefore, the latest and most detailed 

 observations do not tend to support the views of the French school. With respect to 

 the Crinoids, however, the results which Perrier describes himself as ha\dng obtained, 

 fall in with his theory in a manner which leaves nothing to be desired for completeness. 

 In the case of the Urchins, according to Koehler, Perrier saw too little ; while his two 

 hundred Comatula-sections have revealed more to him than has resulted from all the 

 observations of Luchvig, Teuscher, Greefi", and myself; and we, not Perrier, have seen 

 too little. His theory, however, breaks down completely unless he can prove to the 

 satisfaction of his colleagues that the labial plexus and chambered organ of a Crinoid 

 are in direct communication with the exterior through the water-pores of the disk. 



Unless these points can be properly demonstrated, the doctrine that the water- 

 vessels and intervisceral blood-vessels of a Crinoid are only parts of a " vaste systeme 

 aquifere " will have to be abandoned ; while it does not harmonise at all with the present 

 state of our knowledge of the morphology of the Echinozoa, except in so far as this is 

 based upon the observations of the French Zoologists. 



^ Comptes rendus, t. xcviii. p. 1449. 



2 Recherches sur I'Appareil circiilatoire des Oursins, Archivesd. Zool. exp^r.,vol.iv., 1875, pp. 605-643, pis. xxiii., xxiv. 



8 Recherches sur les Echinides des Cotes de Provence, loc. cit., pp. 58-79. 



« Q^cart. Joimi. Micr. Sci., 1883, vol. xxiii., N. S., pp. 597-609. 



^ Beitrage zur Anatomie der Asteriden, Zeitschr.f. wiss. Zool, Bd. xxx. pp. 99-131. 



« Sur TAppareil circulatoire des Etoiles de Mer, Comptes rendu!,, 1882, t. xciv. pp. 658-660. 



