44 THE VOYAGE OF II.M.S. CHALLENGER. 



polyps break up easily, and the reference to a figure of Gosse's which recalls our 

 Epizoantkus cancrisocius, make it probable that his Epizoanthus papiUosus and the 

 Epizoanthus cancrisocius are identical. 



Erdmann refers it in his Memoir to the expedition of H.M.S. "Triton." I find, 

 however, his specimen in a bottle from the Challenger collection, with the label given 

 above ; some mistake must therefore have occurred in his manuscript. 



Genus Corticifera, Lesueur. 



Coenenchyme extending from the base upwards between the individual polyps, and 

 uniting them together almost as far as the upper edge of the body-wall ; integument 

 incrusted ; sphincter mesoglceal ; mesenteries arranged on the microtype. 



On the above diagnosis I may remark that, on the body-wall of each polyp may 

 be distinguished two regions, the one surrounded by coenenchyme, the other projecting 

 freely above it. When the animal contracts, the latter is drawn inwards to the level 

 of the coenenchyme as in Madreporaria ; it partly serves to close over the anterior end, 

 and partly is invaginated inwards. A colony in contraction consec|Ucntly forms a crust- 

 like coverino', in which the individuals are only indistinctly marked off from each other. 



Corticifera lutea* Quoy and Gaimard (PI. I. fig. 6). 



Individual polyps marked off lay fairly obvious stripes on the coenenchyme, and 

 recognisable as annular ridges on the common surface of the colony ; they differ but 

 little from each other in size. 



Habitat. — Bermuda, June 1873 ; shallow water. 



Dimensions. — Height, 1 cm. ; breadth, 0"4-0'5 cm. ; colour, yellowish-white. 



" The colony at my disposal consists of a flat, quadrangular, crust-like structure, 

 about 16 cm. long and 7 cm. broad. It does not present a complete whole, but is 

 merely a piece torn off from a larger mass, carrying about 400 individuals ; the latter 

 reach a height of 10-15 mm., and are in diameter 4-5 mm. It must be insisted 

 that this external height of the polyps in no w^ay corresponds to the internal, since the 

 coenenchyme forms on the under side so thick an investment that of the total height 

 only about two-thirds belong to the coelenteron, the other third to the coenenchymatous 

 layer beneath. All the individuals are strongly contracted, and the body-wall is drawn 

 deeply inwards. The edge of the body- wall projects above the general surface as an 

 annular depressed ridge, in the centre of which lies, always clearly open, the aperture 

 to the interior. At the unmutilated edge the individuals stand out as slight swellings. 



" In that part of the coenenchyme which borders on the ectoderm, are present 

 numerous accretions, producing a firm pellicle. The main bulk of the incrustation 

 consists of irregularly-shaped calcareous bodies ; besides these, occur more sparingly 



