Mr. II. J. Carter on the Snhsjyheroics Sjjonges. 5 



arc a number of dimples or pores more or less regularly scat- 

 tered over the whole sponge, with here and there larger ones, 

 of the same appearance, which seem to be vents. Internal 

 structm-e subradiated, cavernous, consisting of a cortex and 

 body, but no nucleus. Cortex hard, compact, composed of a 

 thin but firm layer of globular crystalloids, apparently in con- 

 tact with each other, covered externally by the dermal sarcode 

 mentioned, and internally in communication with the body, 

 the dermal sarcode presenting minute apertures of communi- 

 cation between the exterior and interior of the sponge ,' and, 

 where abraded, that portion only of this sarcode which is usually 

 stretched across the pore in the form of a diaphragm with 

 central circular aperture some distance below the surface. 

 Body formed of sponge-substance supported on intercrossing 

 stout spicules, which circumferentially run into a zone of 

 radiating ones that support the cortex, and centrically into a 

 denser condition, which is subnuclear ; the whole permeated 

 by an excretory system of wide canals, which, branching and 

 anastomosing throughout, communicate to the body a cavernous 

 subradiated structure, finally terminating in the vents on the 

 sui'face of the sponge. Spicules of the dermal sarcode minute, 

 smooth, slightly cmwed and pointed at each end. Globular 

 crystalloids of the ci-ust more or less elliptical, somewhat com- 

 pressed vertically, and presenting an umbilicated depression 

 on the proximal side ; found in every part of the sponge, in 

 all stages of development, but chiefly forming the crust. When 

 young, consisthig of a minute central point surrounded by a 

 radiated mass of hair-like spicules, which, in advancing to- 

 wards maturity, become conical externally and, giving place 

 to a clear general crystallization of the centre or body inter- 

 nally, terminate at last on the surface in short, rough, club- 

 sha])ed eminences and, polygonal star-like facets (peculiar to 

 the umbilicated depression and convexity resjjectively) sepa- 

 rated from each other by shallow fissures. Spicules of the 

 body large, smooth, fusiform, slightly curved and pointed at 

 each end. Spicules of the zone supporting the crust all smooth 

 and pointed ; provided for the most part with trifid extended, 

 trifid recurved, and triradiate heads, in the pro])ortion of about 

 eight of the two former to one of the latter, which in point of 

 stoutness is more than double their size ; all furnished with 

 long pointed shafts, of which the stout triradiate one is by far 

 the shortest, although the thickest. Mituife stellate spicules 

 found in every part of the structm-e, but most about the crust, 

 inside and out, consisting of a variable number of smooth (?), 

 straight rays, radiating from a central globule ; also some few 

 of a larger kind, In which the rays consist of a number of 



