404 THE VOYAGE OF H.M.S. CHALLENGER. 
NOTE D. 
(Pages 100, 106.) 
ON THE SUPPOSED COMMUNICATION OF THE CHAMBERED ORGAN AND 
LapiaL PLexvus 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 part 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’étude 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 
canals 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 following sentence, “leur plexus se 
continue jusqu’& Vorgane cloisonné dans les chambres duquel s’ouvrent encore chez 
l'Antedon rosaceus les canaux issus des entonnoirs inférieurs du disque.” 
The chambered organ of a Comatula is lodged within the cavity of the centro-dorsal 
basin, covered up by the rosette, and surrounded by the ring of united first radials 
(PL LXI. 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 draw 
attention to these ciliated water-pores ;? and he gives the date of his having done so as 
1872.3. 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 
1 Anatomie des Echinodermes ; sur Vorganisation des Comatules adultes, Comptes rendus, t. xeviii., No. 23, 
1884, p. 1449, 
2 Comptes rendus, t. xcviii. p. 1449. 
* Recherches sur l’anatomie et la régénération des bras de la Comatula rosacea, Archives d. Zool. expér., vol. ii. p. 42. 
* Zum feineren Bau der Crinoiden, Bull. Acad. Sci. St. Petersb., t. xvii., 1872, col. 3-9, Mit einer Tafel. 
