SILICIOUS AND HORNY SPONGES WILSON. 391 



A partially macerated specimen from station D5162 is referable 

 to this species and because of its vasiform habitus may be given 

 a varietal name. 



The sponge is a thick-walled vase, tapering below to a small at- 

 tached base. An axial cloaca, extending throughout the body, opens 

 on the upper end by a large osculum. Total height 125 mm.; di- 

 ameter 60 mm. Diameter of osculum 25 mm. ; cloaca in its upper 

 part as wide as the osculum, diminishing below. Sponge firm but 

 slightly compressible ; light brown in color. 



The dermal membrane has macerated away. The outer surface 

 shows abundant small apertures, mostly 1 mm. or less in diameter, 

 leading into more or lesss radial canals of corresponding size. A 

 large hole, 20 by 12 mm., on the side of the sponge, perforates the 

 wall and leads into the cloaca — probably the result of an injury. 

 A considerable part of the lining of the cloaca is uninjured. This 

 is smooth and shows no apertures. Just beneath it are a good many 

 canals, 3 mm. and over in diameter, which perhaps open into the 

 upper part of cloaca where the lining has been lost. Sponge tissue, 

 in general dense; canals, except those just referred to and a few 

 others, 1 mm. or less in diameter. 



Skeleton a unispicular reticulum with a little spongin at the 

 nodes: meshes triangular, squarish, or polygonal; side of mesh 

 70-190 [j. long and therefore less than the length of a single spicule. 



Spicules. — 1. Oxea, smooth slightly curved, gradually pointed as 

 in the type, not abruptly as in variety canaliculata, about 240 by 9 a. 



2. Sigma, slender, simply contort, 16-20 \l long; abundant. A 

 ft'W larger forms, up to 68 a in length, were observed. It is un- 

 certain if they belong to the sponge. 



3. Toxa, fairly stout, sharply angulated in the middle; not at all 

 common. Specimens measured 28, 32, 40, 52, 68 \l in length; the 

 small forms, 28-32 [Jt, are the more abundant. 



Ilolotype.— Cat. No. 21264, U.S.N.M. 



Genus STRONGYLOPHORA Dendy (1905). 



Stronfft/lophora Dendy, 1905, p. 141. 



Meglascleres are strongyles of various sizes together with, in some 

 species, oxeas. Megascleres partly collected in spiculofibers and 

 tracts, with but little spongin ; these forming a reticulum. A dense 

 cortical layer of the skeletal reticulum may be differentiated. Mi- 

 croscleres in the form of smooth microxeas, chiefly or exclusively 

 found in the dermal membrane. 



I have slightly altered Dendy's original diagnosis (1905, p. 141), 

 to cover the facts presented by the species to be described. — Topsent's 

 new genus, Microxina (1917, p. 72), is placed by its author close to 

 Strongylophora. 



