392 BULLETIN" 100, UNITED STATES NATIONAL MUSEUM. 



STRONGYLOPHORA CORT1CATA, new species. 



Plate 40, fig. 7 ; plate 48, figs. 2, 7. 



A dried specimen, taken at station D5593. Sponge body consists 

 of a branching axis, cylindrical or more often flattened, the branches 

 anastomosing so as to give rise to an irregular mass. Transverse 

 diameters of sponge : In a cylindrical region, 25 mm. ; in a somewhat 

 flattened region, 45 and 30 mm. ; in a very flattened, laminate, region, 

 100 and 30 mm. Total height of sponge 405 mm.; greatest width 

 200 mm. Sponge has a distinct rind about 1 mm. thick, much firmer 

 than the interior, which in the dried specimen is loose and fragile. 



Oscula 5 to 10 mm. in diameter scattered over surface, each lead- 

 ing into a depression into which numerous smaller canals open. A 

 fine dermal skeletal reticulum extends over whole surface, excepting 

 the oscula which are open. Fleshy part of dermal membrane 

 macerated. 



The firm part of the rind consists of a dense subdermal lamella 

 about 0.5 mm. thick, made up of closely packed megascleres, and 

 perforated by rounded apertures (== radial canals), 250-350 [x in 

 diameter. The parts of the lamella between the apertures measure 

 175-250 [x in width. The lamella is doubtless to be looked on as 

 a close reticulum of dense spiculo-fiber. Between the subdermal 

 lamella and the superficial (dermal) skeletal reticulum is a space 

 crossed by radial pillars made up of the large megascleres. Between 

 the pillars lie subdermal chambers, for the most part 250-350 [x wide ; 

 pillars narrow as compared with the chambers, often about 85 jx 

 wide at the middle. In places where the sponge body has been cut 

 across, a second skeletal lamella like the subdermal one may be seen 

 in the inner parenchyma; more or less parallel to the surface of 

 sponge but joining the subdermal lamella at an angle. 



Skeleton of interior, internal to the subdermal lamella, made up of 

 an irregular reticulum and scattered megascleres. The reticulum is 

 composed of dense spiculo-fibers, up to 200 [x thick, and less compact 

 spicule-tracts, grading down to bands 1-2 spicules thick. Dermal 

 skeletal reticulum in general polyspicular ; meshes 100-200 \i in di- 

 ameter; sides of meshes formed by loose tracts of a few megascleres 

 or occasionally by single spicules. Abundant radial tufts of very 

 small oxeas, microxeas, project outwards from the strands of the 

 dermal reticulum, not only from the nodes but from the sides of the 

 meshes. 



Spicules. — 1. The dominant spicule is a strongyle (pi. 48, fig. 2,«), 

 260-315 by 18-22 n, smooth, slightly curved, with evenly rounded 

 ends. Smaller sizes are common, grading down through all sizes to 

 small and relatively very stout forms (pi. 48, fig. 7,a), as small as 

 30 by 9 (x. Small strongyles of a slender type (fig. 7,6), 30-40 by 

 3-5 (x, also occur. 



