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



Astrophjton ccecilia, Ltk., Vid. Mecldel., p. 18, January 1856 ; Addit. ad Hist., part 2, 



p. 157, pi. V. fig. 6. 



Astrojihpfon Krehaii, Orst. & Ltk., Vid. Meddel., p. 18, January 1856 ; Addit. ad Hist., part 2, 

 p. 158, 1859. 



West Indies; 73 to 125 fatHoms. 



Astrophyton clavatum, Lym., Proc. Bost. Soc. Nat. Hist., vol. viii. p. 85, 1861 ; 111. 

 Cat. Mus. Comp. Zool., No. i. p. 191. 

 Zanzibar. 



Gorgonocephalus. 



Gorgonocephalus, Leach, Zool. Miscell., vol. ii., 1815. 



Disk thick and inclined to be circular, and, together with the arms, covered by a 

 thick skin. Arms narrow at their base, and branching by a series of not numerous 

 forks, having between them long, unequal shafts. Eadial shields long and bar-like, 

 composed of overlapping, soldered plates, and extending nearly or quite to centre of 

 disk, thus forming more or less elevated radiating ribs. Margin of disk and inner angle 

 of interbrachial spaces strengthened by irregular horizontal rows of plates. Teeth, 

 tooth papillse, and mouth papillae all similar and spiniform. No true arm spines, but 

 the outer branches have spiniform tentacle scales which, with the tentacles, are found 

 quite to the base of the arm. Both the finer twigs and smaller branches are ringed 

 with double lines of grains bearing microscopic hooks. Side arm plates confined to 

 under surface and lower sides of arm. On the small branches the under arm plates are 

 divided in three pieces, which increase in number towards the base of the arm, and there 

 form an irregular pavement. 



Upper arm plates represented by numerous thin, irregular plates, forming a mosaic. 

 Two genital ojaenings at the outer corners of the interbrachial spaces. 



When I made a first section of a fine Gorgonocephalus piourtalesii, brought back by 

 the Challenger, and whose swollen disk indicated a gravid individual, I expected to 

 find a general arrangement of organs quite similar to that already known in such genera 

 as Opjhiomyxa. My astonishment was considerable when there was brought to light 

 an internal economy which reminded one rather of an orange than of an Echinodcrm. 

 A horizontal cut, just above the joint of the radial shields, disclosed a quantity of 

 membranous partitions stufied with a sort of pulp and radiating in a confused manner ; 

 while a vertical section showed what might be a digestive cavity, surrounded by and 

 communicating with a number of convolutions or blind sacks. The matter became clear 

 only by giving up the idea that a strict correspondence with known forms was to be 

 looked for. 



