REPORT ON THE HEXACTINELLIDA. 349 



flormal skeleton consists, according to Sollas, of numerous rough oxypentacts. No 

 uncinates or scopulse were found. 



2. Dactylocahjx suhglobosus, Gray (PI. XCIX.). 



Through the kindness of Professor 0. Schmidt I obtained the half of an unfortunately 

 much injured and partially macerated dried specimen of that sponge which Gray 

 described in 1867 under the title Dactylocalyx siibglobosus, and figured in the 

 Proceedings of the Zoological Society of London, 18G7, pi. xxvii. fig. 1. I was thus 

 able to study the skeletal structure of this form. While I can, without further comment, 

 simply corroborate the results of Gray and 0. Schmidt as to the general form and 

 macroscopic features, I have been led to some divergent conclusions as to the minuter 

 structure. To these I must therefore briefly refer. Like Gray's specimen, and that 

 figured by 0. Schmidt in his Spongien des Meerbusens von Mexico (Taf. iv. fig. 8), 

 the specimen lent me for examination, and represented from a photograph in the outer 

 view in PI. XCIX. fig. I, exhibited a deep, thick- walled, pear-shaped cup, with a compara- 

 tively broad basis. The wall consists of a much folded plate. The clefts and furrows of 

 the internal surface are narrower and more lonoitudinal than the more irregular cavities 

 and furrows on the exterior. 



While former investigators have seen in the folded plate, which forms the entire wall 

 of the goblet, only a compact mass traversed by small round canals, I find it to be 

 composed of a fine network of anastomosing tubes, 0"3 to 0-5 mm. in transverse 

 diameter. The main direction of the tubes forming the framework is indeed radial to 

 the surface of the entire sponge, but so many lateral branches of equal width are given 

 off in every direction, anastomosing with adjacent tubes, that the whole a^ipears as a 

 thick and irregular felt-work. The cavities and interjacent spaces which occur between 

 these anastomosing tubes, and, of course, communicate with one another in all directions, 

 have the same diameter as the tubes. While I found this intercanalicular system of cavities 

 closed on the inner gastral surface by a reticulated plate, I saw their free apertures here 

 and there on the outer dermal surfiice. Here too, however, they are doubtless covered 

 over by the delicate porous dermal membrane. The water streaming in from outside 

 must find its way first into these interstitial spaces, then through the walls of the tubes 

 into their lumen, and thence into the large gastral space, and perhaps also to the 

 exterior by the dermal terminal apertures which are probably present during the life of 

 the sponge. In fig. 2 of PI. XCIX. I have given a diagrammatic representation 

 illustrating my conception of the structure. 



The dictyonal framework supporting the waU of these narrow tubes exhibits 

 moderately strong irregularly tuberculate beams, with square, triangular, or round 

 meshes without any definite regularity. The parenchyma includes, besides simple 



