284 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Genus CHARACELLA Sollas (1888). 



Characetta Sollas, 1888, p. 91. 

 Massive, sometimes vaselike, also incrusting. Triaenes localized 

 at periphery of body, in the usual position with radial rhabdome. 

 Microxeas present, sometimes differentiated into larger (choanoso- 

 mal) and smaller (dermal) ones. 



CHARACELLA ABBREVIATA, new species. 



Plate 37. fig. 7; plate 45, figs. 7, 10. 



D5513, one specimen. 



Sponge massive, irregular; attached by under surface. Horizon- 

 tal diameters 70 mm., 50 mm.; vertical diameter 40 mm. Upper 

 surface feebly hirsute with oxeas projecting 1-3 mm.; latero-infe- 

 rior surface smooth. Color, light brown. 



Dermal membrane riddled with pores, about 100 ^ in diameter, 

 lying everywhere between the tangential rays of the supporting 

 triaenes. Numerous small oscula, 0.5 mm. and less in diameter, 

 scattered over the surface in general. On the upper surface is an 

 efferent aperture 9 by 5 mm., crossed by a bar of ectosome, leading 

 into a very shallow cloaca, the wall of which is studded with the 

 mouths of canals, 2-3 mm. in diameter. 



Spicules. — (1) Orthotriaene (pi. 45, fig. 10) ; abundant; clads 

 long, tangential, overlapping, in more than one layer, and consti- 

 tuting an irregular reticulum which supports the dermal membrane ; 

 rhabdome short and radial, sometimes aborted and then appearing 

 as a rounded tubercle; all rays smooth, strong, and pointed. Clads 

 300-800 \k long; characteristic size 600-700 by 50-60 [x. Rhabdome 

 commonly 300-350 ljl by 55-70 \l. 



(2) Large oxea (pi. 45, fig. 10) ; characteristic size 2.4 mm. by 

 80-90 [jl; smooth, equiended. Some radial and projecting; others 

 scattered promiscuously in parenchyma. 



(3) Choanosomal microxea (pi. 45, fig. 7, a) ; 150-300 by 5 pt : 

 characteristic size 280 by 5 y.. Very abundant throughout the inte- 

 rior, especially abundant around canals. 



(4) Dermal microxea (pi. 45, fig. 7, b) ; smooth, spindle-shaped, 

 not centrot3 r lote ; 40-60 by 3 \x, commonly about 48 by 3 [x. Abundant 

 in dermal membrane. 



(5) Streptasters (pi. 45, fig. 7, c) ; of the amphiaster type. Axis 

 short and slender, about 4 \i long; rays long, slender, tapering, 

 12-16 [jl long; 3-4 rays at each end of the axis; total length of 

 spicule commonly about 30 [k. Rarely a larger form, of the plesiaster 

 type, occurs: total length 48 \i. with only 4 rays. 



' Holotype.— Cat. No. 21255, U.S.N.M. 



The rhabdome of the triaene is, as said, not infrequently reduced 

 in this species to a tubercle. This variation has been fixed, so to 



