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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 81 



sigmas, and bits of the isodictyal reticulation. A little further re- 

 duction and one would have a Hymjeniaoidon^ which like most every 

 simple sponge genus is probably polyphyletic. 



MYXILLA PARASITICA Lambe 



Myxilla parasitica Lambe, 1893, p. 31. 



Holotype. — In the Museum of the Geological Survey, Ottawa^ 

 Canada. 



Type locality. — The west coast of Canada. 



Material examined. — One specimen was collected January 11, 192.5, 

 in the south end of Monterey Bay, Calif. The University of South- 

 ern California collected three : One on April 19, 1929, at Point Fer- 

 min, near San Pedro ; one without locality data other than depth 30 

 meters; and one without locality data other than depth 60 meters. 

 Descriftlon (U.S.N.M. No. 21473; B.M. No. 29.9.30.15).— Shape,, 

 amorphous. Size, up to 15 mm high, 5 cm in diameter. Consistency,, 

 firm. Color in life and when preserved, drab. Oscules, indistinct,. 



liable to confusion with the 

 pores. Pores, at least 200/x in 

 diameter when open. Sur- 

 face, superficially very ir- 

 regular; there are smooth 

 places, also even more numer- 

 ous lumps and depressions. 

 Ectosomal specialization 

 obscure, doubtful. Endo- 

 somal structure, a typical 

 myxilloid isodictyal reticula- 

 tion. Histological details : 

 The flagellate chambers are 

 subspherical, about 25/j(, in 

 diameter. 



Principal spicules, acanthostyles (fig. 45, B) ; size, 10/^ by l70/x to 

 15/i, by 200/A. Ectosomal spicules, hastate tornotes (fig. 45, A) ; size,. 

 7)u, by 170/i, to 11^ by 210/x. First microscleres, anchorate chelas (fig. 

 45, G) ; length, 48/a to 68/*, Second microscleres, anchorate chelas 

 (fig. 45, D)\ length, 14/a to 18/*. Third microscleres, sigmas (fig.. 

 45, E, F) ; length, 22/* to 52/*. 



Remarks. — The specimen collected by the University of Southern 

 California differs from the Monterey specimens in the shape of the 

 larger chela, its median tooth being very much smaller than the 

 corresponding one in the sponge from central California. This 

 variation within the species is surprising, but the agreement in other 

 ways is so striking that there need be little hesitation in identifying 



Figure 45. — Myxilla parasitica Lambe, X 300 



