628 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXVI. 



It apparently formed an irregular mass some 10.5 cm. long and 

 2 cm. thick, coating a piece of stick, but has unfortunately been 

 much damaged in transit and now consists for the most part of loose 

 powder and gemmules. The color (dry) is a pale gray. The surface 

 so far as it remains, is smooth, with fairly large oscula (about 3 mm. 

 in diameter) , which are not raised on eminences. The external mem- 

 brane has Avholly perished. The substance of the sponge is com- 

 pact, the primary radiating 

 fibers, but not the secondary 

 transverse ones, being visible in 

 a vertical section to the naked 

 eye as slender white threads. 

 The gemmules, which are prac- 

 tically colorless, are numerous 

 throughout the sponge. 



/2 \/ • ^ ^>-^^;::r;;:v-....-^.^^vx>3^ 



X360 z 



XJ240 d X240 



Fig. 1. — SPo.NtJiLLA .sfi;i'TiaoiDEs. a, skelkion si'ui i.ks ; b, <iE.\i.Mi le .sticules. 



The largest skeleton spicules measure 0.35 mm. by 0.021 mm. They 

 are straight or feebly curved and are covered with extremely minute 

 projections in the central part of their length, the ends, which are 

 sharply and cleanly pointed, being smooth. The projections are so 

 minute that it is often difficult to see them. They are conical in out- 

 line, somewhat broad at the base in comparison with their length, 

 and are rarely sufHciently numerous to give the spicules a roughened 

 look under a low power of the microscope. 



I can find no flesh spicules. 



The gemmule spicules measure from 0.12G mm, to 0.147 mm. in 

 length. They are slender in proportion (transverse diameter about 

 0.00-12 mm.) and straight or feebly curved. The spines which cover 

 them with fair uniformity are about half as long as the spicule is 

 thick; those in the middle are straight, those at either end curved 

 and directed backward. As a rule the spicule terminates at either 

 end in a single straight spine. 



