SILICIOUS AND HORNY SPONGES WILSON. 361 



brushes are, for the most part, distinctly inequiended, about 1 mm. 

 by 8 jx, the thicker end the outer, (c) A very few long slender spinu- 

 late oxeas, about like those of T. splnosa, occur in the oscular fringe 

 and protrude over the general surface. 



2. Protriaene. (a). The common and conspicuous form protrud- 

 ing over the general surface has a rhabdome 1.5-0.9 mm. by 6-7 [x, 

 clads 80-40 by 3-4 ^; rhabdome as usual tapering from near the 

 cladome to a very fine end; clads straight, often somewhat unequal 

 in length in the same spicule, (b). Slenderer forms occurring with 

 the foregoing, having longer and outwardly curving clads. Rhab- 

 dome about 2 mm. by 3-6 [x; clads reaching 140 fx in length, (c) 

 Hair-like forms occur in abundance along with (a) and (b) ; rhab- 

 dome about 1 [x thick; clads outcurving, 20-40 [x long. The specific 

 name calls attention to the presence and the location of these spicules 

 which doubtless are young forms, in the sense that they constitute 

 the stock from which class (b) is recruited, (d). Protriaenes of the 

 root bundles have a long rhabdome of the usual shape, reaching 7 

 mm. by 14 [x, and long straight clads, 100-180 [x in length, (e) . 

 Protriaenes of the oscular fringe are chiefly strong spicules with 

 straight clads; rhabdome 6.7-3.5 mm. by 10-20 [x, clads 160-100 by 

 5-8 [x. Inner part of the fringe includes many smaller protriaenes, 

 in which the clads are only 25-35 [x long. 



3. Anatriaene, occurring in the root tuft and in the radial bundles 

 of the lower end of the body. Rhabdome of usual shape, over 8 

 mm. in length, 8-10 jx thick; clads about 40 [x long. 



4. A single plagiotriaene, resembling those figured by Dendy for 

 T. poculifera (1905, p. 90), was observed. 



5. Sigmas, 10-20 jx long, abundant throughout the interior and 

 at the dermal and gastral (cloacal) surfaces. In the interior the 

 spicules measure 10-16 jx. In the ectosome small sizes are abundant, 

 but larger ones, 16-20 [x, are also common. In the gastral membrane, 

 the spicules measure 10-12 jx. 



IJolotype.— Cat. No. 21312. U.S.N.M. 



The species is close to T. poculifera Dendy (1905, p. 90). The 

 most essential difference is the absence of a small oxea (microxea), 

 about 230 [x long, which constitutes a conspicuous element of the 

 skeleton in T. poculifera. 



There are suggestive resemblances to T. spinosa of this report. 



TETILLA SPINOSA, new species 



Plate 39, fig. 3. 



Station D5146, one specimen. 



Sponge obconical with the truncated base somewhat convex, 60 

 mm. high, 35 mm. thick. A single osculum, 2.5 mm. in diameter, at 

 81709—25 7 



