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



colony appears to be irregularly covered with knobs. These knobs exhibit radial 

 furrows which run outwards from the indistinct opening. 



Habitat. — Simon's Bay, Cape of Good Hope ; 10-20 fathoms. 



Dimensions— OS-OS cm. in height; diameter, 0"2-0"5 cm. 



Colour. — Brownish. 



The small colony of about forty individuals differs essentially from the above 

 described Corticifera lutea in its external appearance. From the small development of 

 ccenenchyme, it results that the individual polyps press closely on one another, and 

 frequently become polyhedrally, generally hexagonally, flattened. They are separated 

 by deep grooves on the surface, which, at few points only, become shallower or dis- 

 appear altogether. The absence of the groove between two polyps possibly signifies a 

 genetic dependence, the one having arisen by gemmation from the other ; and smaller 

 individuals are "frequently adjunct to the larger polyps in this fashion. 



The individuals of the colony are of most varying size ; from the large dome- 

 shaped convex animals with a diameter of 0'6 mm. those of intermediate size lead to 

 the smaller, which measure only 0"1 mm. in the one direction and 0'2 mm. in the 

 other. Since the surface therefore exhibits smaller and larger knobs, I refer the species 

 to the Palythoa tuberculosa of Klunzinger, and have therefore retained the well-chosen 

 specific name. 



In length there is but little difference between the larger and smaller animals, the 

 former measuring 6 cm., the latter 0"4 cm. As they all diminish downwards in a 

 wedge-shape, the lower side of the colony is so much narrower that the polyps on the 

 edge are nearly horizontal. 



All the polyps are so strongly contracted that the entrance to the interior is 

 recognisable only as an indistinct indentation, from which radiate outwards numerous 

 shallow furrows. 



With reference to the finer anatomy, what has been said for Corticifera lutea 

 holds good in this species. In the two specimens investigated there were respectively 

 thirty-four and thirty-six mesenteries, which followed the microtype. 



Genus Palythoa, Lamouroux. 



Integument strongly incrusted ; ccenenchyme little developed, ribbon- or tongue- 

 like ; mesenterial arrangement on the macrotype ; sphincter endodermal. 



Palythoa anguicoma* Norman (PL I. fig. 7). 



Incrustation superficial, so that a thick layer of mesoglcea remains free of deposit ; 

 ccenenchyme tongue-shaped ; individuals, when in a contracted condition, long, with a 

 terminal capitular enlargement, on which run 15-20 radial furrows. 



