404 • THE VOYAGE OF H.M.S. CHALLENGER. 



NOTE D. 



(Pages 100, 106.) 



On the Supposed Communication of the Chambered Organ and 

 Labial Plexus with the Exterior. 



Perrier's statements respecting the direct continuity of the water-tubes depending 

 from the oral ring of the larva with the inner ends of the water-pores of the disk have 

 recently been extended to the adult Antedon. He further asserts not only that some of 

 the water-pores open into the more or less glandular tubules of the labial plexus, but 

 also that the canals forming the inner ends of the water-pores on the lower j)art of the 

 disk open into the cavities of the chambered organ. ^ 



I will not go so far as to deny the truth of these statements ; but can only say that 

 the results which Prof. Perrier believes himself to have obtained by " 1' etude minutieuse 

 de plus de deux cents coupes " are far from being in accordance with those of Ludwig, 

 Greeff, Teuscher, or myself. It seems to me unlikely that the complex relations of the 

 (■anals forming the inner ends of the water-pores which Perrier describes should have entirely 

 escaped the notice of all of us. I freely admit that I may have overlooked the connection 

 of the water-pores with the water-tubes and with the labial plexus ; for the state of preser- 

 vation of my material has not been such as to yield sections of one-fortieth of a millimeter 

 thick. But, on the other hand, I have carefully studied many more than two hundred 

 sections, nearer two thousand in fact, of several different types ; and I believe it to be 

 impossible that I could have avoided seeing such a connection between the water-pores 

 and the chambered organ as is described in the follomng sentence, " leur plexus se 

 continue jusqu'jt I'organe cloisonne dans les cliambres duquel s'ouvrent encore chez 

 Y Antedon rosaceus les canaux issus des entonnoirs inferieurs du disque." 



The chambered organ of a Comatida is lodged within the cavity of the centro-dorsal 

 basin, covered up by the rosette, and surrounded by the ring of united first radials 

 (PI. LXr. fig. 2). It is therefore a perfect mystery to me how any of these canals which 

 lead inwards from the ciliated water-pores and traverse the perisome of the disk can 

 possibly open into its chambers. 



Perrier describes himself as having been the first since the time of Miiller to cbaw 



O 



attention to these ciliated water-pores ; - and he gives the date of his having done so as 

 1872.^ In making this claim, however, he entirely ignores the fact that on the 21st 

 of March 1871 Grimm had communicated a description of them with illustrative figures 

 to the St. Petersburg Academy.^ His description and figures were published in 1872, and 



^ Anatomie des !l6chinodermes ; siir I'organisation des Comatules adultes, Comptes rendus, t. xcviii., No. 23, 

 1884, p. 1449. 



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



^ Recherches sur I'anatomie et la r^g(5n6ration des bras de la Comatula rosacea. Archives d. Zool. exper., vol. ii. p. 42. 



* Zum feineren Bau der Crinoiden, Bull. Acad. Sci. St. Petersb., t. x\-ii., 1872, col. 3-9, Mit elner Tafel. 



