SILICIOUS AND HORNY SPONGES WILSON. 317 



spine sometimes appearing as an enlargement. Rays are numerous, 

 often about 10 seen at one focus. 



9. Oxyaster of choanosome: abundant, with no, or only a very 

 small, centrum; total diameter 32-40 ji., ray length 12-16 p.; number 

 of rays commonly 9-12. Rays relatively long, spinose at extreme 

 end ; the outstanding spines together with the apex of the ray mak- 

 ing a small terminal crown, about as in Lendenfeld's acanthtylaster 

 (Lendenfeld, 1906, p. 289). The terminal crown is more evident in 

 the larger spicules but is perhaps always present. 



The above is the dominant and characteristic aster of the choano- 

 some, but other asters occur here ranging over to the form with large 

 centrum and numerous rays. Smaller oxyasters of all sizes, down to 

 spicules with a diameter of 4 pi, also occur in the choanosome. These 

 have relatively long, sharp rays, and are probably stages in the de- 

 velopment of the larger spicules. 



Holotype.—Czt. No. 21267, U.S.N.M. 



GEODIA JAPONICA (Sollas), var. SPHERULIFERA, new variety. 



Plate 38, fig. 1. 



Cydonium japonica Sollas, 1888 p. 256. 



Geodia japonica (Sollas) Thiele, 1898, p. 7. — Lendenfeld, 1903, p. Ill: 

 1910, pp. 72, 235. 



A specimen sufficiently close to G. japonica to be best listed as a 

 new variety was taken at station D5355. The body is a circular 

 cake-shaped mass with convex upper surface bearing in its center 

 a large shallow depression or cloaca. Horizontal diameter 100- 

 110 mm., vertical thickness 40-60 mm.; cloaca 35 by 25 mm. wide, 

 and about 15 mm. deep. Sponge firm, even hard, compact. Color, 

 whitish brown. 



Surface in general now glabrous, although there are in places 

 megascleres projecting a few millimeters. The whole surface is 

 covered with a dermal membrane, uniformly perforated with closely 

 set pores; where this has been rubbed off, the chone canals open 

 on the surface (artefact). The chone canals are distributed 

 throughout the whole cortex and are alike everywhere; each ex- 

 pands above into a saucer-shaped subdermal cavity (chone vesti- 

 bule). Very generally over the surface the roofs of such cavities 

 are depressed, perhaps a contraction effect, while between them the 

 trabeculae of sponge tissue, covered likewise by the porous dermal 

 membrane, form low ridges. Thus a reticular appearance visible 

 to the eye is produced, in which the depressed areas are a frac- 

 tion of a millimeter in diameter and the intervening trabeculae 

 have about same width. In flat surface preparations the chone 

 vestibules give a star-shaped appearance, as in Lendenfeld's fig- 



