352 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



species, to Stylocordyla (see Hentschel, 1909), which differs from 

 Rhazaxinella apparently only in the oxeate character of its mega- 

 scleres. (See Ridley and Dendy, 1887, p. 222). 



RHIZAXINELLA NUDA. new species. 



Plate 38, fig. 5. 



A specimen from station D5512. 



The body is club-shaped, about 55 mm. long, 21 mm. thick, rounded 

 above, tapering below, and continued into a hard, bare stem. 

 The latter is irregularly cylindrical, 60 mm. long, 4—6 mm. thick, and 

 ends below in a thin plate-like expansion. A small osculum nearly 

 closed is eccentrically placed on the upper end of the body. 



Color very light brown; stem darker. Sponge firm and compact. 



Surface of body without eminences, covered with a fine furze of 

 projecting spicules. Stem is continued into body as an axial bundle 

 of spicules, about 3 mm. thick. This ascends two-thirds of the way 

 through the body breaking up at its upper end into indistinctly 

 marked radial tracts, which project upwards and outwards. 



The skeleton of the parenchyma of the body consists of large 

 smooth fusiform tylostyles, more or less radially arranged and reach- 

 ing the surface ; not grouped in well-marked bundles ; mostly about 

 2 mm. by 50-60 [x. The degree of tapering from the middle toward 

 the ends of the spicule is considerable; the point is sharp; head 

 small but well marked. 



The skeleton of the body includes also a dense ectosomal crust of 

 similar but smaller tylostyles, 600-1,200 by 14—30 jx, which project 

 about 0.5 mm. from the surface. The ectosomal spicules are ar- 

 ranged in conical tufts, the spicules of a tuft diverging. The tufts 

 (bouquets) are however closely set and overlap, so that at and be- 

 yond the surface the crust is continuous and not broken up into 

 groups of spicules. 



Stem of sponge is stony without a covering of parenchyma and 

 without the ectosomal crust. It is made up of a dense mass of longi- 

 tudinally arranged and interwoven tylostyles. Some of these are 

 like those of the body parenchyma. Many however are slenderer, 

 nearly cylindrical, and with rounded apex, often becoming tylotes 

 (tylote strongyles). These are slightly curved in an irregularly 

 sinuous fashion; 1,500-3,200 by 28-44 |x. Transitions between the 

 two types occur. 



The axial bundle of spicules in the interior of the body includes 

 both the slender sinuous tylostyles or tylotes and the stouter straight 

 fusiform tylostyles. The latter reach a greater length, 3 mm., here 

 than in the parenchyma and are commonly rounded at the apex. The 

 sinuous megascleres are relatively less abundant in this axial bundle 

 of the body than in the stem proper. 



