68 PROCEEDINGS OF THE NATIONAL MUSEUM vol.81 



only 10 cm high and 6 cm in diameter and is stipitate but not funnel- 

 shaped, being instead rather lobate. It agrees with the funnel- 

 shaped specimens except that it seems to have no sigmas at all, but 

 instead a few toxas about 4)m by 400^. It has also numerous palmate 

 isochelas about 22/a long, which may be foreign, yet several species of 

 Mycale are recorded with such microscleres in addition to the typical 

 amoschelas. That they and the toxas may not be proper is indicated 

 by the finding of a few such obviously foreign spicules as some 

 piesiasters, tylotes, and short renierid oxeas, but the isochelas are 

 quite numerous. The surface of this specimen is also notably dif- 

 ferent, in having a distinct oscule 4 mm in diameter and definite con- 

 tractile dermal pores, one to three to each square millimeter of 

 surface. 



MYCALE MACGINITIEI8 ^e Laubenfels 



Mycale macginitiei de Laubenfels, 1930, p. 26. 



HoIohjpe.—U.S.l^M. No. 21471 ; B.M. No. 29.8.22.3. 



Type locality — Elkhorn Slough (intertidal) on the east shore of 

 Monterey Bay, Calif., collected by Prof. G. E. MacGinitie, March 1, 

 1929. Several years ago a pile of rocks was dumped at one place in 

 this area of tidal mud flats, and this sponge and a Halisarca have now 

 appeared encrusting them. 



Description. — Shape, encrusting. Size, less than 1 cm thick. 

 Patches mostly less than 6 cm in diameter. Consistency, mediocre. 

 Color in life and when preserved, drab. Oscules, not evident. Pores, 

 about 30ju in diameter and about 70/x from center to center. Surface, 

 superficially smooth. 



Ectosomal specialization, a dermal membrane; very thin, detach- 

 able, jfleshy, contains spicules in confusion. Endosomal structure, 

 " crumb-of-bread," with fibers; little or no reticulation is present. 

 Principal, or ascending, fibers YO/i, to lOO/z, in diameter, cored by many 

 spicules, but with little spongin. Below the surface they expand in 

 brushes, the most divergent spicules being actually within the dermis. 



Principal spicules, subtylostjdes (fig. 36, J.); size, 9/* by 250/x to 

 10/x by 280ju,. First microscleres, palmate anisochelas (fig. 36, B)\ 

 length, 30/1, to 36ju,, often in rosettes. Second microscleres, palmate 

 anisochelas (fig. 36, C) ; length, about 13fi. Third microscleres, toxas 

 (fig. 36, Z?) ; length, 45/x to 75/x. Fourth microscleres, sigmas (fig. 

 36, E) ; length, 60/x to 75/i. The microscleres are distributed generally 

 throughout the flesh. The toxas are very rare. 



Remarks. — The nearest relatives of this species seem to be the 

 Mycale macilenta Bowerbank, 1866, from Great Britain (recorded by 

 Hentschel in 1912 from Australia), and Mycale aegagropila Bower- 



' Named for Prof. G. E. MacGinitie, of Stanford University, who discovered this sponge. 



