the MorjpJiology of the Echinoderms. 117 



BtroDgly as I do from the French authors, Messrs. Perrier, 

 Koehler, and Apostolid^s, respecting the supposed communi- 

 cation with the exterior of the so-called blood-vascular sys- 

 tem in Urchins and Ophiurids, through the pore-canals of the 

 madreporite. It is on this last point, which deals with fact 

 and not with theory, that, like Ludwig, I am at variance with 

 what 1 ventured three years ago to call " the French school." 

 My reasons for the " prevention " referred to by Prof. Perrier 

 are twofold. 



In the first place, I do not believe many of their statements 

 of fact to be correct, as I distrust the nature of the evidence upon 

 which these are based ; and, secondly, there is far too strong a 

 tendency, especially in the case of Professor Perrier, to make a 

 sweeping generalization upon data which are either altogether 

 inadequate or even absolutely incorrect. An excellent in- 

 stance of the latter kind is afforded by Prof. Perrier's state- 

 ment respecting the presence of radiating cavities at the 

 syzygies of the Stalked Crinoids, which I have discussed 

 above. 



The greater part of his publications upon the morphology 

 of the Crinoids have been limited to what he himself de- 

 scribes * as " quelques fragments isoles " of his results. 

 Some of his earlier statements have been profoundly modified 

 in later communications, while others have been tacitly with- 

 drawn. Among the latter, for example, is the expression of 

 his conviction that no one will ever find the coeliac canal of a 

 Crinoid f, although he now tells us that it commmiicates with 

 the exterior through pores at the syzygies of the arms. After 

 having once asserted that the cirrus-stumps of a Pentacrinoid 

 larva alternate with those of the arms J, in spite of the evi- 

 dence to the contrary in the descriptions and figures of 

 Dr. Carpenter § and M. Sars |l, Prof. Perrier now tells us % 

 that the cirri and the arms are " superposed," a fact that 

 has been known for the last twenty years. Then, again^ 

 Prof. Perrier ** claims to have " demontre " that the inter- 



* Zool. Anzeiger, 1885, p. 267. 



t " Recherches sur I'Anatomie et la Regeneration des Bras de la 

 Comatula rosacea" Arch, de Zool. Exper. et Gen^r. t. ii. 1873, pp. 48, 49, 

 73. 



X " Sur la d^veloppement des Comatules^'' Comptes Rendus, tom.xcviii. 

 1884, p. 446. 



§ Phil. Trans. 1866, pis. xl., xU. 



|| ' Crinoides vivants, tab. v. p. 53. 



11 Zool. Anzeiger, 1885, p. 264. 



** " Sur une Asterie des grandes profondeurs de I'Atlantique, pourvue 

 d'un pedoncule dorsal," Comptes Rendus, t. xcv. 1882, p. 1381. 



