HYALONEMA (HYALONEMA) POLYCAULUM. 201 



slender-rayed basal spicules are about twice as large, and the inicrohexactines 

 are smaller, and composed of more strongly curved rays in the former than in 

 the latter; the large macramphidiscs of H. (H.) obtusum reach 356 ^ in length, 

 have shafts bearing large spines along their whole length and possess anchors 

 the end-parts of whose teeth are parallel to the shaft ; the large amphidiscs of H. 

 (H.) agassizi are not over 310 yu long, have shafts destitute of large spines outside 

 the centre, and possess anchors the end-parts of whose teeth diverge ; the end- 

 parts of the anchor-teeth of the large micramphidiscs are in the former far more 

 curved than in the latter. 



Hyalonema {Hyalonema) polycaulum is in outer appearance, apart from its 

 polycaule nature, similar to the forms described as C, D, and E. It differs from 

 this species, however, by its large macramphidiscs, its pinules, and its mode of 

 attachment to the sea-bottom. The large macramphidiscs are in the sponges 

 described above considerably shorter, have relatively narrower anchors and 

 anchor-teeth much more strongly curved in their distal part and less divergent, 

 than in Hyalonema (Hyalonema) polycaulum. The distal rays of the pinules 

 of the former are considerably thickened above the middle and have a stout 

 terminal cone. In those of the latter such a thickening above the middle is 

 either absent or very insignificant, and the terminal cone is much more slender. 

 It is also to be noted that the distal rays of the pinules of the sponges described 

 above bear more numerous spines than those of Hyalonema (Hyalonema) poly- 

 caulum. The former is attached by a single stalk; the latter by several stalks. 



Hyalonema (Hyalonema) polycaulum, sp. nov. 

 Plate 53, figs. 1-17; Plate 54, figs. 1-45. 



One specimen of tliis species was trawled in the eastern part of the Tropical 

 Pacific at Station 4721 on 15 January, 1905; 8° 7.5' S., 104° 10.5' W.; depth 

 3811 m. (2084 f.) ; bottom composed of Ught brown Globigerina ooze. It appears 

 to have possessed four distinct stalks. To this the specific name refers. 



Shape and size. The single, somewhat fragmentary specimen (Plate 53, 

 fig. 4) is oval, 54 mm. long, 48 mm. broad, and somewhat flattened. Only slight 

 remnants of the dermal membrane are left, the specimen appearing very porous 

 in consequence. A group of large cavities, separated by thin plates, occupies 

 one of the flat faces. A thickening at the joining hne of these plates, which, 

 however, does not project freely, is, as its internal structure shows, a gastral cone. 

 The large cavities around it are parts (diverticula) of the gastral cavity. On the 



