SILICIOUS AND HORNY SPONGES WILSON. 435 



been lost. On the whole, however, it seems best not to separate 

 them from the other Coelosphaeras, but to regard the cylindrical 

 shape of the megasclere as the culmination of an evolutionary tend- 

 ency which begins to show itself even in the typical species of the 

 genus. In a revision of genera I suggest that these species be set off 

 from the type as a subgenus. 



Topsent, 1894c? (p. 11), enumerated the species of the genus known 

 at that time. Lundbeck, 1910 (pp. 25-26), has given a more recent 

 list in which, however, some of the forms are referred by him to 

 other genera. He includes Sideroderma navicelligerum Ridley and 

 Dendy, for which Dendy, 19216 (p. 105), substitutes the new name 

 Siderodermella. To Lundbeck's list may be added : C. (Histoderma) 

 verrucosa, var. fucoides Topsent from Amboina (Topsent, 1897, p. 

 452), C. (Histoderma) dichela and var. gracilis Hentschel from the 

 Aru Islands (Hentschel 1912, pp. 343, 345). 



COELOSPHAERA TOXIFERA, new species. 



Plate 42, fig. 7 ; plate 49, fig. 6. 



One dried specimen from station D5640. Sponge massive, 100-130 

 mm. high with horizontal diameters of 160 and 300 mm. The body, 

 which is covered with a firm rind, bears on its upper and lateral 

 surfaces very numerous (about 75) tubular processes, 5-10 mm. in 

 diameter. The ends of most of these fistulae are broken off but are 

 present in the case of a few, which may be seen to taper somewhat 

 to a rounded closed extremity. The complete fistulae are 30 mm. 

 or less in length. One of them is terminally branched, dividing into 

 three short processes. 



What appear to be three cloacal apertures, 20-40 mm. in diameter, 

 lie on the upper surface. These seem to be natural and lead, each, 

 into a depression into which open several canals. The whole under 

 surface is much incrusted; it was evidently attached and is without 

 appendages. 



The skeletal framework is made up of strong spiculo-fibers, often 

 0.5 mm. thick, consisting of closely packed megascleres; spongin 

 almost absent. In the body the spiculo-fibers are combined to form 

 reticular laminae about 0.5 mm. thick, the apertures in which are 

 0.5 mm. or thereabouts in diameter, while the spiculo-fibers between 

 the apertures are somewhat less than the diameter of the latter. 

 Such reticular laminae are disposed more or less parallel to the 

 surface of the sponge, 1-3 mm. apart. Between them extend 

 trabeculae of spiculo-fiber, forming a coarse, irregular reticulum. 



The dermal membrane of the body is very thin, shows no pores, 

 and is filled with closely packed megascleres of all sizes, arranged 



