110 BIOLOGICAL. SURVEY OF 



these species are identical but due to the inadequacy of Ver- 

 rill 's prior description it is thought best to consign the present 

 specimens to Suberites concinnus. 



Geographical distribution. [Suberites compacta.) Off 

 Martha's Vineyard (Verrill and Smith), Arctic Ocean, Beh- 

 ring Sea, North Pacific Ocean (Lambe), Mount Desert 

 Region. 



Polymastia Bowerbank 

 Polymastia robusta Bowerbank 



Bowerbank (1866, p. 62; 1874, p. 23, pi. 10, figs. 5-8; 1882, 

 p. 31). Lambe (1896, p. 195, pi. 2, figs. 6, 6a-b). 



This species was taken at Stations D 52, 73, 75, 102, on 

 rock, depth 34 to 38 feet. 



There are seven specimens of this species and they range in 

 size from a small circular one, 20 mm. in diameter, with a 

 single fistula, to one 50 mm. long and 30 mm. broad, having 

 17 fistulae. These fistulae are usually not over 20 mm. long 

 with a diameter of 3 mm. However, in one of the specimens 

 the fistulae are unusually long and graceful, the longest one 

 being almost 40 mm. in length. There are no visible openings 

 at the distal ends of these fistulae. These specimens were 

 found growing on rocks. According to Whiteaves, this 

 species may be several inches in length. 



Skeleton consists of stout fibers (.243 to .324 mm. in diam- 

 eter) perpendicular to the surface. Upon approaching the 

 cortical layer these fibers expand slightly, extend through this 

 layer, and project a bit beyond the surface of the sponge. 



In the outer part of the cortical layer there is an abundance 

 of small spicules, closely packed, and perpendicular or slightly 

 oblique to the surface. When the surface is viewed in profile 

 under the microscope these spicules are seen to project very 

 slightly, thus giving the surface a slight hispidity which is 

 not observable by the unaided eye. 



In the inner cortical layer the spicules are larger and ar- 

 ranged for the most part parallel to the surface, but other- 

 wise with no definite arrangement, as they lie scattered in all 

 directions. 



