322 p. HEEBERT CARPENTBB. 



numerous pores in the interpalmar areas of the disc are in 

 direct continuity with the tubes depending from the water- 

 vascular ring in the lip, just as he asserts to be the case in 

 younger larvae. If this be true, then he has discovered a fact 

 which has escaped the notice of Grimm, Greeff, Teuscher, Ludwig, 

 my father, and myself; and the sooner he gives us a straightfor- 

 ward description and figure of it, the better. If, however, this 

 is not his meaning, one would like to know what relation 

 between the water-pores and water-tubes he really does intend to 

 describe. He states in his concluding resume that "jusqu'k 

 cet age les pores qui font communiquer la cavite generale 

 avec Pexterieur peuvent etre consideres comme les orifices de 

 tubes hydrophores avec lesquels ils sont lies tout h fois par 

 leur nombre et leur position." It is difficult to reconcile this 

 with his previous assertion respecting the absolute continuity 

 of the primary water-pore and water-tube without the inter- 

 vention of the body-cavity. 



The most startling statements which he makes, however, are 

 those relating to the homologies of the problematical struc- 

 ture which I have called the plexiform gland. It has been 

 designated by a variety of names, as is shown in the following 

 list -.1 



Perrier stated in his note of last July, and rightly, as I 

 believe, that " L^organe dorsal des Crinoides a la meme struc- 

 ture que le pretendu coeur des autres Echinodermes.^' Eut he 

 now says that while the water-pores and water-tubes of a 

 Crinoid " ne correspondent nuUement an canal du sable 

 (water-tube or stone-canal) des autres Echinodermes; ce canal 

 du sable parait au contraire represente par Torgane axial des 

 Comatules, qui possede tout a fois la structure du canal du 



^ W. B. Carpenter, 1875, 'Axial prolougatiou.' 

 Greeff, 1876, ' Drusenartige dorsoveutral Gefassaxe.' 

 Ludwig, 1877, ' Dorsales Organ ;' 1880, ' Centralgeflecht.' 

 P. H. Carpenter, ISSl, 'Central plexus,' 



Perrier, 1883, ' L'organe dorsal,' ' Le glaude ovoide,' 'Le corps ovoide.' 

 P. H. Carpenter, 1SS3, ' Plexiform gland.' 

 Perrier, 1SS4, ' L'orgaue ovoide,' 'L'organe axial.' 



