368 Transactiojis . 



Genus Bunodes. 



Bunodidce with tubercles arranged in vertical series. Only the series 

 corresponding to the mesenteries of the 1st cycle run the full length of the 

 column. Marginal spherules on edge of disc. 24 pairs of mesenteries, 

 12 of them perfect, and all fertile except the directives. 



Bunodes aureoradiata, n. sp. 



Specific Character. — Yellow radii in 6 groups of 3. 



Pedal-disc. — Adherent ; slightly wider than the column ; the edge 

 undulate to correspond with the vertical rows of tubercles. On each undula- 

 tion are 2 or sometimes 3 perforations, through which, when irritated, 

 the animal projects nematocysts torpedo-fashion, and in such a manner 

 as at first sight to suggest feeble acontia. 



Column. — Cylindrical. In full expansion it is higher than the breadth. 

 The lower half is light or yellowish-brown, upper half greenish-brown. 

 There are 24 vertical rows of tubercles or verrucee : near the bottom of the 

 column these become mere markings ; they increase in size as they ascend 

 the column, culminating in a row of 24 white beads at the bases of the outer 

 cycle of tentacles. The rows of tubercles correspond to the endocoeles of 

 he mesenteries ; they consist of evaginations of the body-wall, and contain 

 ctoderm, mesogloea, and endoderm ; they are perforated, and probably 

 are able to act as suckers. The ectoderm of the column contains numerous 

 nuclei, fairly regularly arranged. Cell outlines are indistinguishable in my 

 preparations, but the nuclei are so arranged as to suggest that they belong 

 to long narrow cells. The mesoglcea consists of fibres imbedded in a struc- 

 tureless vacuolated matrix, in which are also a few other immigrant cells 

 from the ectoderm and the endoderm. There are no nematocysts. The 

 endoderm here, as in all parts of the body, contains symbiotic zooxanthellse, 

 which are present in very large numbers. The circular muscle of the wall 

 does not appear to be regularly developed through the whole length of the 

 wall. 



Tentacles. — Conical and gently tapering. Pore at tip. Colour bronze- 

 green, like that of the oral disc. The tentacles are very sensitive, and 

 completely and quickly retractile ; they number 48, and are arranged in 

 4 cycles, the formula being 6 -|- 6 + 12 -t- 24 =^ 48. The ectoderm of the 

 tentacles is thinner than that of the column. The epithelial layer contains 

 numerous nuclei, but no cell-walls are distinguishable. There are numerous 

 nematocysts. The nervous layer of the ectoderm appears as a fibrous net- 

 work, with here and there what are apparently nerve-cells. The longitudinal 

 muscles of the tentacles appear as pleatings of the mesogloea. The meso- 

 gloea is not so distinctly fibrous as that of the column ; it is thin and vacuo- 

 lated. The structure of the endoderm is almost completely obliterated by 

 the great numbers of zooxanthell;^ that are present. A few folds on the 

 ondodermal side of the mesogloea indicate the circular muscles of the 

 tentacles. 



Sphincter Muscle. — In transverse sections of the upper part of the column 

 the sphincter appears as a ring *ly^ng in the angle formed by the wall of 

 the oral disc. In cross-section it is seen to be well developed, endodermal, 

 and of the circumscribed type, not unlike the sphincter of Cradactis digitata 

 figured by McMurrich.* 



* ■■ Scientific Results of Explorations by the United States Fish Commission Steamer 

 ' Albatross ' " (Proc. U.S. Nat. Mus., vol. xvi, pi. xxxiii). 



