32 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 81 



Sficulation. — The dictyonal framework is supported by a single- 

 layered network in most parts and occasionally by a two or more 

 layered irregular network. The framework is always quadrangular 

 in those portions near outer margins of the tubes and becomes irregu- 

 lar in the lower portions. The beams of the framework are micro- 

 tuberculated on the surface. From the center of the crossing point 

 of the beams, a prominent, fairly long, rough-surfaced, and nearly 

 conical boss projects. 



The dermal and gastral pentactins (fig. 4, a) of this species meas- 

 ure commonly 430/* to 460/i, in length of the paratangential rays. 

 The proximally directed, unpaired ray is usually the same as the 

 paratangentials of the same spicule, except that they are slightly 

 shorter. Near the center the rays are 12/a to 16/* thick. All the rays 

 gradually attenuate toward the more or less conically pointed end. 

 The surface is roughened except for a short distance near the center, 

 the roughness becoming gradually more pronounced toward the ends. 



The clavulae are, broadly speaking, of two kinds, namely, circular 

 umbellate clavulae and anchorate hooked clavulae. The circular 

 umbellate clavulae (fig. 4, h) are fairly abundant here and there, 

 penetrating vertically to the surface, and form small bundles around 

 the unpaired proximal ray of the dermal pentactin. There is no 

 swelling on the shaft, except just below tlie umbel, which measures 

 about 16/1 in width and has 16 to 18 minute teeth on the periphery. 

 The shaft is very slender and attenuated gradually to the pointed 

 end, usually about 300/t long. The surface is sparsely roughened, the 

 roughness being most pronounced on the swelling of the shaft, just 

 below the umbel. 



Several variations of the anchorate hooked clavulae occur in dif- 

 ferent regions of the same sponge. This variation is, on the one 

 hand, associated with the shape of the terminal disk, and on the 

 other, with its terminal spines. I distinguish two forms or varieties 

 which are designated by the letters A and B. 



Form A (fig. 4, c, e) is represented chiefly in the dermal layer and 

 is arranged vertically to the dermal surface. It is large and strong 

 and is provided with long curved spines, 48/i to 95/i long, forming a 

 disk 64/1 to 105/x broad across tips of spines, and 30/i to 40/x broad 

 across the club-shaped basal swelling, which is externally roofed over 

 by a hemispherically arched umbel, raised on the center into a pro- 

 jecting boss, or infrequently Avith a nearly smooth convex umbel. 

 The shaft is generally simple, straight, 590/i to 680/* long, 8/* to 12/i 

 broad at the base, and gradually attenuated toward the conically 

 pointed end and covered wdth sparsely scattered spines on the distal 

 end, while the proximal end near the terminal disk is covered with 

 numerous strong, long, curved spines, projecting obliquely from the 

 shaft. 



