Note on Dendrobrachia fallax Brook. By J. A. Thomson. 14;; 



twelve polyps examined. It was impossible to cut the extremely 

 brittle tissue, and the tentacles split very readily up the middle, but 

 in four or five cases there seemed no doubt as to the presence of 

 eight. Brook was not able to determine the number. In one case 

 it seemed fairly certain that there were, eight mesenteries. 



The occurrence of eight pinnate tentacles at once suggests an 

 Alcyonarian, and one was reminded that in many cases Alcyonid 

 Alcyonarians grow over the naked axes of Gorgonids so thoroughly 

 that a very deceptive appearance results. There is not, however, 

 anything — such as uncovered tips on the twigs, or hummocking of 

 the ccenenchyma — to lead one to suppose that the specimen is not 

 a unity. Moreover, there is no hint of Alcyonarian spicules, and 

 the pinnules on the tentacles are much more irregular than in 

 Alcyonarians. One would not indeed consider this possibility, 

 were it not that some cases of the masking of extrinsic axes by 

 Alcyonarians are almost incredibly deceptive, and were it not that 

 the type in question is such a puzzling Antipatharian. 



That Antipatharians have affinities with Zoantharians seems 

 probable, and it is interesting to remember that the primitive type 

 Edwardsia has only eight complete mesenteries, that a young 

 Halcampa has eight tentacles, and that some sea-anemones, e.g. 

 Adinodendron, ha ye irregularly pinnate tentacles. There seems to 

 be little doubt that Dendrobrachia fallax is a primitive Anti- 

 patharian, nearer than many to the Zoantharian stock. One 

 would like to see more of it. 



Brook's two specimens were dredged in 1876 from 425 fathoms 

 off Ascension ; those now exhibited were dredged in 1901 from 

 219 fathoms off the island of St. Vincent, in the Caps Verde 

 Islands. 



