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



The dermal skeleton is composed of medium-sized, strongly developed hypodermal 

 pentacts, in which the smooth rays, gradually narrowed towards the extremity, are either 

 simply conical or somewhat roughened and rounded at the tips. Besides these, the 

 dermal membrane includes numerous teti'acts and pentacts, and more rarely diacts, with 

 central nodes. These dermalia correspond exactly to those of Cratcromorpha meyeri. 

 Their straight and rough rays intersect at right angles, and the ends are thickened in 

 somewhat club-shaped fashion. 



The gastralia, which form a connected layer lining the gastral cavity, resemble the 

 dermalia, and consist, for the most part, of pentacts with small tubercles or bosses in the 

 place of the sixth ray. Hexacts also occur, in which the projecting radial ray extends 

 for a greater or less distance into the gastral cavity. The canalaria lining the inner 

 surface of the wider efferent canals resemble those just described. The skeleton of the 

 stalk does not essentially differ from that of the bell-shaped body. 



4. Crateromorpha tumida, n. sp. (PI. LXVIL; PL LXVIII. fig. 2). 



Near the Banda Islands (Station 194a, lat. 4° 31' S., long. 129° 57' 20" E.), 

 from a depth of 360 fathoms and a volcanic mud ground, the trawl brought up two 

 specimens of a Crateromorpha, in which the very soft body proper has been badly 

 preserved, and so much injured by subsequent friction during transport, that only a 

 cloudy formless mass remains attached to the firm stalk. Fortunately a figure 

 (PI. LXVIL fig. 1) of one of the specimens had been previously made under Sir Wyville 

 Thomson's direction, which shows at least the form of the body before ft was so much 

 damaged. The specimen measures 17 cm. in length. The cylindrical stalk is firmly 

 attached to a compact basal plate, and from its thinnest portion, just above the basal 

 plate (where it measures about 5 mm. in breadth), gradually increases in diameter on to 

 the base of the body, where it attains a breadth of 20 mm. Where the smooth and firm 

 stalk passes into the body, there is a trumpet-shaped expansion with projecting radial 

 ridges and depressions between. The body proper measures 13 cm. in breadth by 8 cm. 

 in height, it exhibits irregular lateral bulgings, and has on the whole the form of a broad 

 cup with very thick walls and with sharp superior margin. The irregular undulating 

 edge of the superior aperture is approximately circular and measures almost 10 cm. in 

 diameter. 



The irregularly ridged and furrowed external surface of the body is covered by the 

 delicate lattice-work of the dermal membrane, through which one can see the numerous 

 round lacunte (1 to 4 mm. wide) of the afferent canal system. The somewhat firmer 

 internal surface of the wide, almost hemispherical gastral cavity, exhibits in its upper 

 marginal region comparatively small apertures of the efterent canal system, which 

 beeome gradually larger, however, towards the lower surface. It is noteworthy, as a 



