SPONGES COLLECTED IN PORTO RICO. 
897 
Cape Cod to South Carolina. In it the surface exhibits no spinose projections, but bears, at compara- 
tively great intervals, large projecting processes. Beneath the comparatively uniform surface, buried 
in the sponge body, are, however, small, closely set, horny columns, projecting upward from the 
basal plate. These columns may anastomose, the radial growth which leads to the production of 
the columns continuing from the new level thus formed. Where the sponge body is thin and the 
columns are free from one another, the horny skeleton is essentially like that of M. spinosa, except 
that the columns are closer and the surface is not molded over them,, as in the latter form. The 
megascleres are very similar in the two species. In M. prolifera the large stylus measures about 250 
by 16 p; and the head, which may or may not be (in same specimen) most minutely tuberculate, is 
somewhat more marked (tylostylote condition) than in M. spinosa. Isochelae 16 p long, and toxas 40 
p long, are present, but in very small number. The data given relate to Beaufort (North Carolina) 
specimens of M. prolifera. The indication is that the two sets of forms may intergrade. 
Genus CLATHRIA 0. Schmidt (1862). 
“Skeleton a reticulation of fiber, usually with much spongin, cored by smooth styli and echinated 
by spined styli. Typical microscleres, small palmate isochelae” (Dendy). In addition to isochelae, 
toxas may be present. 
Clathria clathrata (O. Schmidt). 
Tenacia clathrata , O. Schmidt, 1870, p. 56. 
Station 6079, one specimen. 
From Schmidt’s description, the following is drawn: Sponge body consists of cylindrical branches, 
which may anastomose freely or may be widely divergent. Horny skeleton exceedingly well 
developed. Fibers yellow, echinated abundantly with spined styli; including long styli, more 
commonly tylostyli, and many spined styli. In the spined stylus the shaft, immediately below 
spinose head, is smooth; rest of shaft spinose; the sharp-pointed end again smooth. Chelae something 
over 10 p long. Very slender toxas and sigmas? ( Spangen ) present. Ends of the horny fibers extend 
out into the easily separable dermal layer. From each such end radiate spicules, not united by 
spongin, in a thick bundle. In the dermal layer are numerous brushes, 'spicules in a brush radiating 
in very divergent fashion. Between the brushes lie the same spicules, partly in tracts, partly scattered. 
In the Porto Rico specimen the body is divided dichotomously into a few slender subcylindrical 
branches, 5 to 8 mm. diameter. Branches widely divergent on one side of specimen, on other conflu- 
ent, in typical Clathria fashion. Surface smooth, except for scattered, mostly small, protuberances. 
No oscula visible. Consistency firm, hard. Color, light gray. Total height of specimen, which is 
not entire, 150 mm. 
Skeleton. — Reticulum, formed by the stout, horny fiber, is dense and massive, nearly filling the 
sponge body, but stopping short of the surface. From it extend out, vertically to surface, closely set, 
short, strong, horny processes, which are very thickly echinated with the spined styli. 
Spicules: (1) From the ends of the processes, comparatively stout, smooth styli, 300 by 10 p or 
somewhat smaller, radiate; mingled with these may be equally long but slenderer subtylostyli or 
styli. (2) Megascleres, imbedded in horny fibers and scattered in parenchyma, are chiefly slender, 
smooth, subtylostyli, 200 by 4 p to 350 by 6 p-, with some strictly stylote forms. (3) Spined stylus, 
echinating and included in horny fiber, 50 to 60 p by 5 p. (4) Dermal brushes and tracts made up of 
smooth, slender subtylostyli, 100 by 2 p to 200 by 4 p. Microscleres. (5) Isochelse commonly 12 p 
long; smaller ones present. (6) Toxas about 60 p long, together with elongated toxas, passing by 
transitions into greatly elongated rhaphides, all together forming a loose bundle. No sigmas found. 
Clathria jugosa, n. sp. 
San Antonio Bridge, San Juan, one specimen. 
I follow Dendy (1895, p. 31) in merging Rhaphidophlus Ehlers (1870) in Clathria. If Rhaplii- 
dojMus were to be retained, the species here described would fall in that genus. But such a form as 
Clathria clathrata Schmidt shows how impracticable it is to divide forms with, from those without, a 
dermal crust. 
Sponge body laminate, 130 by 50 mm. with thickness of 10 mm. Lamina bifurcates at one end, 
plane of division being that in which lamina is compressed; both surfaces covered with conuli about 
