420 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



organism forms a practically solid white calcareous layer, about 5 

 mm. thick, at the periphery of the entire sponge and is continued 

 down as a thinner lining layer into some of the canals. Over most 

 of the body it now constitutes the outer surface of the mass and 

 from it the fistulae rise up. Only over the upper surface is the 

 smooth outer layer of the sponge itself still preserved, underlaid by 

 the calcareous layer within which, as within a rind, lies the sponge 

 pulp. After treatment with acid, the calcareous layer is seen to be 

 made up of the sponge skeletal reticulum and the branching, ap- 

 parently cylindrical, body of the alga, which has everywhere grown 

 between the fibers of the reticulum. The alga evidently infests the 

 outer layer of the choanosome, just beneath the ectosome (dermal 

 layer plus what Ridley and Dendy, 1887, call the bast layer). It 

 converts this into a calcareous rind, outside of which remains the 

 sponge ectosome which tends to break and peel off. The complete- 

 ness of the calcareous rind coupled with the presence of the sponge 

 pulp within it seems to demonstrate conclusively that some of the 

 fistulae must be afferent and others efferent, for they provide the 

 sole channels of connection between the sponge pulp and the sur- 

 rounding water. Where the ectosome has been left, as on the 

 upper surface of the sponge, it tends to rise up and form low 

 blister-like swellings. The Challenger specimens seem to exhibit 

 something of this appearance, in that the surface is said to be " very 

 uneven and covered with numerous bladder-like, almost glabrous 

 swellings." 



The Challenger specimens and Lamarck's came from Australian 

 waters. The fistulae taken by the Challenger in the Atlantic (off 

 Bahia) and the specimen described by Topsent (1892, p. 74) from 

 the Azores are very doubtfully referred by Ridley and Dendy and 

 by Topsent respectively to this species. 



PHLOEODICTYON CAGAYANENSE, new species. 



Plate 42, fig. 3; plate 48, fig. 10. 



One specimen from Station D5423 (off Oagayan Island in the 

 Jolo Sea). Sponge massive, elongated, 60 mm. high, 40 mm. in 

 transverse diameter, incrusted at lower pole with a leathery alcyona- 

 rian. There is a firmer cortex about 1 mm. thick, the outer layer of 

 which is smooth and stony. Sponge tissue internal to the cortex, 

 dense but fragile. Surface covered everywhere with very numerous 

 fistular tubes, mostly 1-2 mm. in diameter, a few reaching a diameter 

 of 3-4 mm. The tubes, which are mostly 4-5 mm. apart, are all 

 broken off, the longest projecting only about 2 mm. Wall of the 

 tubes stony, a prolongation of the cortex; thin, only a fraction of a 



