362 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the upper pointed end, leads into a small cloaca about 4 mm. deep, 

 on the floor of which several (five) efferent canals open. Upper and 

 lateral surface smooth, and set off rather sharply from the base which 

 bears small protuberances and is covered with root bundles. The 

 root bundles penetrate and hold a mass of shelly debris and foramini- 

 fera, about as large as the sponge body. Color, a light yellowish 

 brown. Sponge firm and compact. Ectosome collenchymatous with 

 small subdermal cavities. Pores scattered over surface between the 

 protruding ectosomal brushes of spicules. Parenchyma with abun- 

 dant embryos. 



The skeleton consists of — 



1. Closely set conical ectosomal brushes, about 700 [x deep, protrud- 

 ing only slightly at the surface. 



2. Radial bundles of large megascleres. 



3. Scattered parenchymal oxeas of many sizes. 



4. Long bundles of slender megascleres which descend from the 

 interior of the sponge to the basal surface or beyond it, in the latter 

 case forming the root bundles. 



Spicules. — 1. Smooth parenchymal oxea, of many sizes up to 3.8 

 mm. by 40 [x ; the two ends not noticeably dissimilar ; scattered every- 

 where, the larger nearer the center of the sponge. 



2. Large, smooth oxea, 1.5-2 mm. by 28-40 jx; inequiended, the 

 thicker end being the outer ; in radial bundles. 



3. Ectosomal oxea, 400-650 by 2-6 [x ; smooth ; inequiended, thicker 

 end the outer ; in the ectosomal brushes. 



4. Spinose oxea, 3 mm. by 6-8 [x; inequiended, thicker end the 

 outer. The spines project inwards, are fairly strong in the larger 

 spicules, feeble in some of the slenderer. In the radial bundles and 

 moderately abundant, although distributed without any apparent 

 regularity. 



5. Slender ectosomal protriaenes. Rhabdome 500 by 2 jx; clads 

 still slenderer, 12-16 [x long. The most abundant spicule in the ecto- 

 somal brushes. 



6. Larger protriaenes. Rhabdome 3 mm. by 7-10 [x; clads 30-100 

 [x long. In radial bundles. 



7. Anatriaenes, forming the root bundles and the bundles which 

 descend from the interior to the basal surface of the sponge. Rhab- 

 dome very long, certainly 1 cm.; 12 jx thick near cladome, tapering 

 quickly to 4 [x, thickening again gradually to 8 [x, and finally taper- 

 ing gradually toward the point. Clads 60-76 [x long. 



8. Sigmas. Commonly 8-12 |x long, but reaching 16 or even 20 [x 

 in length. Abundant at the surface and in interior. 



The species is especially characterized by the spinose oxeas, in less 

 degree by the slenderness of the small protriaenes. 

 Holotype.— Cat. No. 21303, U.S.N.M. 



