THE SPONGES. 



95 



in the larger 



Thenea lamelliformis, sp. nov. 



Plate 12, Figs. 10-13; Plate 13, Fig. 1. 



Diagnosis. Body a comparatively thin plate, irregularly polygonal in outline. Both 

 surfaces hispid, with small oxeas projecting about 1.0 mm. ; these abundant in places, 

 scanty elsewhere. A number of marginal pore areas. Oscula scattered over upper 

 surface. Slender rootlets scattered over under surface. Megascleres : dichotriaenes, 

 anatriaenes, oxeas. Micro scler es : spirasters ; total length, 30-40 /x ; ray length, 12-16 jx. 



Station SJflJf, 2 specimens. 



The body (Fig. 13, Plate 12) is a comparatively thin plate, the habitus 

 resembling that of Thenea wrightii Sollas (Sollas, 1888, p. 63, Plate VIII. , 

 Figs. 11-20). The outline of the plate is irregularly polygonal, and 

 round the margin are a number of separate pore areas, — 

 specimen eleven. Over the upper surface are scattered several — in the 

 larger specimen eight — oscula, the openings of depressions into which 

 debouch several efferent canals. The oscula have the usual white, tumid 

 wall, and lack a spicular fringe. Some of them are nearly closed, appear- 

 ing small and slit-like ; others widely open, 5 mm. in diameter. The upper 

 surface is comparatively flat, but the under surface is more uneven, and 

 bears, scattered over it, a number of very slender rootlets. The rootlets 

 are broken off short of the ends, but some measure 20 mm. in length ; 

 diameter at the base, 0.5 mm., the rootlet tapering toward the extremity. 

 The body of the sponge measures 7-8 mm. in thickness, thinning away 

 toward the edge, which is pretty sharp. The larger specimen has a 



greatest width of 72 mm. 



The color is gray. The surface, wherever clean, looks somewhat gela- 

 tinous and translucent. It is hispid, with small oxeas, projecting for the 

 most part not over 1.0 mm., but with these are intermingled here and 

 there oxeas projecting 3-4 mm. 



Between some of the pore areas the margin of the body is indented, 

 the portions bearing the areas projecting and appearing as vaguely indi- 

 cated marginal lobes (comp. Sollas, 1888, p. 63). The pore areas them- 

 selves are depressed, short in the vertical axis of the body, elongated 

 in the horizontal plane, measuring in the latter direction 10-15 mm. 

 There is every evidence that the margins of the areas are highly con- 

 tractile (Vosmaer, 1882, p. 8). The margins are white, tumid, and in 





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