IN THE MORPHOLOGY OF THE CTSTIDEA. 43 



US, either that the primitive Echinoderm had no madreporite at 

 all, or that it was situated in a radial plane, so that its inter- 

 radial position in later forms must be " ein Stiick stark gefalschter 

 Entwicklungtigesehichte." Even if we suppose that a inadreporic 

 canal was present but opened through the osculum, as the oviducts 

 must have done, the facts of embryology altogether preclude the 

 possibility of our regarding this as iu any way a primitive or 

 ancestral condition ; and I believe the same to be the case with 

 Neumayr's doctrine respecting the primitive nature of the apical 

 system in Bothriocidaris. 



PosTSCEiPT (September 1891). 



1. The DoTsocentral System. 



It has been pointed out above (pp. 33-39) that the views of 

 Sladen and myself respecting the fundamental identity of the 

 abactinal or dorsocentral system throughout the calyculate 

 Echinoderms have not been favourably received by MM. Neumayr, 

 Semon, and Sarasin. I am glad to say, however, that Pro- 

 fessor Perrier, who formerly contested our position, has recently 

 adopted it. 



We were led, on various grounds, to doubt the correctness of 

 his assertion that the primary interradial plates in the abac- 

 tinal system of the young Asterias and Brisinga become the 

 odontophores of the adult. In consequence of our criticisms, 

 lie reinvestigated the question in 1885, and still maintained that 

 his former statements were correct'*. Even as late as 1888 he 

 wrote :— 



" Les cinq pieces intei-radiales deviennent, sans contestation possible, les 

 odontoiphores chez les Brisingidcs. Les figures de Loven, mes observations sur 

 Ae^ewms Asterias spirahilis ns me permettent guere de douter qu'il en soit 

 aiusi chez certains Asteriadce, quoique M. Fewkes m'ait affirme que I'odonto- 

 phore se forme d'uue maniere independante chez VA. heri/lina " f . 



Eurther investigation of larval Asterids, however, and also 

 Eewkes's published observations J, have quite recent!}'- led Perrier 



* " Premiere Note preliminaire sur les Echinodermes recueillis durant les 

 campagnes de dragages sous-niarius du ' Travailleur ' et du ' Talisman.' I. Stel- 

 lerides." Ann. Sci. Nat. 6me gerie, Zool. tome xix. 1885, Article No. 8, p. 45. 



1" " Notions actuellement acquises sur I'organisation des Echinodei'mes," 

 Biblioth. Ecole d. hautes Etudes, Sci. Nat. tome xxxiv. 1888, Article No. 4, 

 p. 81. 



t Bull. Mus. Comp. Zool. 1888, vol. xvii. pp. 40-42. 



