SPONGES COLLECTED IN PORTO RICO. 
383 
supported by a reticulum composed of the tangential rays of dermal pentacts. The projecting rounded 
ridges also seen on outer surface, between the furrows, are perforated by numerous small apertures. 
On the inner (gastral) surface of the sponge are the mostly separate, rounded or elongate, sometimes 
confluent, apertures of the efferent canals, which extend out into the above-mentioned ridges. 
Skeleton . — Meshes of dictyonal framework mostly triangular; beams covered with fine tubercles; 
nodes not thickened; slender tubercle-like bosses projecting freely on the bounding surface. Dermal 
membrane contains roughened pentacts; tangential rays usually somewhat dilated at the end, forming 
a supporting mesh work; proximal radial ray tapering, often no longer, or even shorter, than tangential 
rays, in other cases longer (as in Schulze’s diagnosis). Very similar but smaller pentacts are arranged 
round the canals, the tangential rays lying in the canal wall, radial ray extending away from the canal 
longer than the others. 
In the parenchyma are found: (1) Oxyhexasters, delicate, variable spicules; terminals, of which 
there may be two, three, or four, somewhat undulating; some of the principal rays occasionally undi- 
vided. (2) Sphserohexasters of variable size and with a variable number of terminal rays. 
Subclass II. DEMOSPONGI^E Sollas. 
Order I. TETRACTINELLIDA Marshall. 
Some or all of the scleres are tetraxons, trisenes, or desmas. 
Suborder CHORISTIDA Sollas. 
Without desmas. Megascleres not articulated to form a coherent skeleton. 
Family TETILLID/E Sollas. 
Characteristic megasclere is a. protrisene. Microscleres when" present are sigmaspires, but the 
sigmaspires are not infrequently absent. 
Genus CHROTELLA Sollas (1886, 1888). 
Ectosome is a cortex, excavated by subdermal cavities, and furnished with tangentially disposed 
spicules. 
Chrotella minuta, n. sp. 
Station 6070, one specimen. 
Sponge body ovoidal, colorless, 6 mm. long by 5 mm. wide, with thickness of 4 mm., somewhat 
flattened on what is probably the under surface. Surface covered with small conuli, from which 
radiating bundles of long and diverging spicules project to a distance of 800 to 1,600 p. Cortex, about 
500 j-i thick and very translucent, is occupied by a single layer of rounded subdermal spaces, about 
300 fi deep, lying between the radiating spicular bundles. Cortex collenc.hymatous, deepest layer 
having fibrous appearance, owing to fusiform cells running tangentially. No oscula. Pores, few in 
number, open into subdermal cavities. 
Skeleton. — Megascleres. (1) Oxea fusiform, smooth, 2 to 2.5 mm. by 40 //; ecactine stouter than 
esactine. Spicule confined to and fairly abundant in the radial bundles. (2) Protrisene; rhabdome, 
2.2 mm. by 24 // above, tapering to a very slender hair-like termination below; cladi 200 // by 25 ju 
at the base, tapering to a point, noticeably incurved at apex; sagitta 160 // with chord 240 )i ; confined 
to and most abundant spicule in the radial bundles. (3) Anatrisene; rhabdome, 2 mm. by 20 p just 
below cladome, then narrowing to diameter of 8 //, which is preserved close to the fine point; cladi 60 ft 
in length with chord 110 fi and sagitta 48 //, to 120 p in length with chord 220// and sagitta 70//; 
cladome with apical prominence; confined to and much the least abundant smcule in the radial bundles. 
(4) Scattered irregularly and in great abundance throughout choanosome, between the radial bundles, 
are small smooth isoactinate oxeas about 425 // by 8 //. Some of these spicules extend out into the 
deepest layer of the cortex, where they occupy a tangential or oblique position. 
Microscleres. (5) Sigmaspire 12 // long; abundant in dermal membrane and throughout cortex, 
especially in wall of subdermal cavities; common, but not abundant throughout choanosome. 
The specimen is possibly merely a young form. It is much like C. simplex Sollas (Sollas 1888, p. 
17, pi. ii, figs. 1-4), differing chiefly in the presence of the abundant small oxeas and in the possession 
of conuli. Less important differences concern the size of the radial spicules and the degree to which 
they protrude. 2d -F. c. B. 1900—25 
