164 BULLETIN OF THE BUREAU OF FISHERIES. 
The surface of the sponge is formed by a dermal membrane 20 to 4o p thick, the body of which 
consists of not very closely packed mesenchyme cells, which are elongated parallel to the dermal surface 
and the neighboring spaces. The dermal membrane is traversed by closely set, short, radial canals, 
75 to 125 win diameter and about 3o to 60 p apart. These open internally into large subdermal spaces. 
At the outer dermal end these canals are now closed in by thin membranes, each of which in life is 
probably perforated by several pores. In the actual specimen the pores are closed. The subdermal 
spaces are wide just beneath the dermal membrane, but, descending vertically from the surface, they 
become gradually narrower, terminating in the inhalent canals, which are not marked off by any 
definite limit from the subdermal spaces. The subdermal spaces and the inhalent canals open directly 
by small prosopyles, about 4 to 8 « in diameter, into the flagellated chambers, which are generally, 
but not invariably, longer than wide, 80 to 130 # long, 60 to 100 # wide, and which open directly by 
wide mouths into the exhalent canals. 
The Beaufort sponge is probably to be looked on as a migrant from the coast farther 
south. A Bahama species of Aplysilla is known, A. compressa (Carter), but this is an 
erect lamellar form (Lendenfeld, 1889, p. 704). 
The Mediterranean species, A. sulfurea F. E. Schulze, recorded also from Australian 
seas, the European coast of the North Atlantic, and from Juan Fernandez (Thiele, 1905, 
p. 488), resembles the Beaufort sponge in color, the yellow turning to violet in alcohol 
(Topsent, 1904, p. 56), or gradually becoming blue as the sponge dies in the air (F. E. 
Schulze, 1878). The conuli are much lower than in the Beaufort sponge, only 0.5 to 
1 millimeter high and about 1 millimeter apart. 
The Beaufort sponge is nearer to an Australian form, A. violacea (Lendenfeld, 
1889, p. 704). ‘This is an incrusting species with unlimited lateral growth and conuli 
about as high as in the Beaufort species. The conuli are, however, more closely set, 
and the natural color is dark violet. Moreover, there is a basal spongin plate which 
contains large sand grains, and the flagellated chambers are smaller (60 to 100 » long 
by 30 to 4o # wide) than in A. longispina. 
Recent writers (Topsent, 1905; Dendy, 1905 and 1916; Row, 1911; Hentschel, 1912) 
do not separate the Darwinellide and Aplysillide of Lendenfeld’s monograph (1889), 
but combine them in one family, for which Topsent uses the heading, Darwinellide, 
thus following in essentials Merejkowsky (1879) and Vosmaer (1887). The other authors 
cited above use the name Aplysillide. Topsent is obviously in the right, since the type 
genera of the families combined, Darwinel/a F. Miiller and Apiysilla F. E. Schulze, were 
established in 1865 and 1878, respectively. 
Family SPONGELID/. 
Keratosa with eurypylous and large flagellated chambers, with a skeleton com- 
posed of separate horny fibers that ascend from the base of the sponge and are simple 
or branched, or the skeleton is more commonly reticulate. Horny fibers without pith, 
generally containing abundant foreign mineral particles. Skeleton may be reduced, 
then consisting of foreign particles usually held together by a little spongin, but the 
latter may be absent. 
Pleraplysilla Topsent. 
Thin, incrusting forms, with low conuli, supported by spearate areniferous fibers 
ascending from base of sponge and characteristically undivided, 
