142 THE VOYAGE OF H.M.S. CHALLENGER. 



and therefore oldest of these new joints are most like those of the corresponding part of 

 the arm in the adult, i.e., triangular or very slightly quadrate, but relatively wide 

 in proportion to their length. These characters, however, do not disappear as they do in 

 the adult, where the joints become gradually shorter and shorter, with a markedly 

 triangular outline. But throughout the remainder of the restored arm the joints are 

 quadrate and comparatively long ; while the two lowest pinnule-joints show but few traces 

 of the flattening and peculiarities of outline which are so characteristic of the adult. It 

 is just in these characters, besides the smaller size of the first pair of pinnules, that 

 Antedon quadrata differs from Antedon eschrichti, and it is therefore to be regarded as 

 a permanently immature form of the latter species. Levinsen, indeed, considers the 

 two species as identical, a point which I shall discuss when treating of Antedon quadrata. 



Two Pentacrinoids, besides that of Antedon tenella, were dredged by the "Porcupine" 

 in the cold area of the Faeroe Channel ; but I doubt whether either of them can be the 

 one referred to by Sir Wyville Thomson 1 in the following passage : — "A single example of 

 a pentacrinoid in an early stage was found associated with Antedon escrichti. It 

 resembles closeby the larva of Antedon sarsii, but the specimen was not sufficiently 

 preserved for a critical examination." 



The larva mentioned in the above passage is possibly that which I have represented 

 on PL XIV. fig. 2. Its developmental condition is intermediate between the second and 

 third stages of the larva of Antedon tenella, though I do not think that it can be referred 

 to that type, on account of its greater robustness, and for other reasons. But, on 

 the other hand, I do not imagine it to be the larva of Antedon eschrichti, to which 

 species I referred it conjecturally in 1884, 2 together with the larva represented on fig. 3 

 of the same plate. 



The Danish exploring vessel "Dijmphna" dredged forty-five individuals of Antedon 

 eschrichti in the Kara Sea. They were of all sizes from a length of 25 mm. upwards. 

 One Pentacrinoid was also obtained and has been figured by Levinsen. 3 It is considerably 

 younger than the smaller of two Pentacrinoids which were obtained by the Dutch ship 

 " Varna," in the Kara Sea, during the summer of 1883, and were sent to me for examina- 

 tion. 4 I had been unable to definitely refer them to any specific type, but they are so 

 closely similar to that figured by Levinsen that I have now no doubt of their belonging 

 to Antedon eschrichti. It is equally clear to me, however, that the larva which is 

 represented on PL XIV. fig. 2 cannot belong to Antedon eschrichti, as seemed possible 

 in 1884 ; while it is too large for the corresponding stage of Antedon tenella, so far as I 

 can judge from the figures and dimensions of the latter which are given by Sars. 



1 Proe. Roy. Soe. Edin., 1872, vol. vii. p. 764. 2 Proc. Roy. Soc. Edin., 1884, vol. sii. p. 364. 



3 Kara-Havets Echinoderrnata, Dijmphna-Togtets zoologisk-botaniske Udbytte, Kjtfbenhavn, 1886, p. 34 (414) Tab. 

 xxxv. fig. 8. 



4 The proofs of this Report were corrected early in 1885, but for some reasons with which I am not acquainted, it 

 has not yet been published. 



