CAULOPHACUS SCHULZEI. 49 



The remaining nineteen specimens, one of which is represented on Plate 9, 

 fig. 28, are larger. Their irregularly o^^al discs are 40-64 mm. long, 34-54 mm. 

 broad, and 7-12 mm. tliick in the middle. The more or less eccentric and 

 oblique stalk is, near its point of insertion, 2.5-7.5 mm. thick and quite rapidly 

 attenuated below. The disc is flat, slightly convex or concave. The greater 

 part or the whole of the marginal portion of the upper face is convex, so that 

 the margin appears shghtly bent down. 



The stalk is not intact in any of the specimens, but there are among the 

 fragments three rather long stalks with intact lower (distal) end. These are 

 30-40 mm. long, curved, particularly near the base, and 2 mm. thick (at the 

 lower end) to 3.3 mm. (at the upper end). One of these stalks (Plate 9, fig. 28) 

 appears to have been torn off the larger specimen. In the photograph this 

 stalk is artificially attached to it. 



The specimens examined by Wilson (loc. cit., p. 43, Plate 4, fig. 3) were 

 smiilarly composed of a calyculate, flat, or somewhat convex disc-shaped body, 

 22-50 mm. in diameter, and a stalk invariably broken. 



The colour of all the specimens in spirit is brownish gray. 



General structure. Remnants of a superficial membrane supported by the 

 lateral pinule-rays can be made out both on the dermal and the gastral faces 

 of the sponge. This membrane lies on both sides, 70-100 ju above the level 

 occupied by the lateral rays of the hypodermal and hypogastral pentactines. 

 In the intervening space shreds of tissue are observed, indicating that in life 

 this zone was occupied by a network of trabeculae. Below the level marked by 

 the lateral pentactine rays subdermal and subgastral cavities occur, which lead 

 into canals extending more or less transversely, often through the greater part 

 of the thickness of the whole disc (Plate 8, figs. 28, 29; Plate 9, fig. 32). The 

 entrances to these canals are clearly visible, both on the dermal and the gastral 

 face of the disc-hke body. WTiere the superficial membrane is still present, 

 they are covered by it; where tliis membrane has been lost, as is the case on 

 nearly the whole of the surface in most of the specimens, they are freely exposed. 

 The apertures of the dermal face resemble in shape and arrangement those of 

 the gastral face, but are on the whole somewhat larger. The largest are always 

 formed on the central part of the disc. Towards the margin they become 

 smaller. Their distance from each other is in proportion to their size; the 

 marginal ones he much closer together than the central ones. The largest cen- 

 tral apertures are 0.8-4 mm. wide, their width being, on the whole, in proportion 

 to the size of the specimen. Apertures over 3 mm. in diameter have been 



