ART. 4 



SPONGES OF CALIFORNIA DE LAUBENFEL.S 



79 



smooth principal spicules as against Myxilla's usually spiny principal 

 spicules. Topsent separated Lissodendoryx originally on just this 



difference. 



Genus MYXILLA O. Schmidt 



MYXILLA AGENNES de Laubenfels 



Myxilla agennes de Laubenfels, 1930, p. 27. 



Holotype.—V.S.'^M. No. 21415 ; B.M. No. 29.9.30.14. 



Type locality. — The one specimen was collected February 16, 1924, 

 by the University of Southern California at Point Fermin near San 

 Pedro, Calif., intertidal. 



Description. — Shape, amorphous. Size, 25 mm high, 30 mm in 

 diameter. Consistency, mediocre. Color in alcohol, drab. Oscules 

 and pores, not evident. Surface, superficially very lumpy. 



Ectosomal specialization, a dermal membrane; this is 20jii to 60/x 

 thick, not readily detachable, fleshy, and contains almost no spicules 

 at all, but those present are tornotes. Endosomal structure, " crumb- 

 of -bread," with very numerous spicules, often in confusion, but oc- 

 casionally in vague isodictyal reticulation, and again sometimes in 

 ascending plumose col- 

 umns ending in surface 

 protuberances. 



Principal spicules, 

 styles usually curved or 

 bent and usually' quite 

 smooth, but now a n d 

 then with a few spines. 

 Size, 7ju, by 155/a to lOju, 

 by 175/A. There are a 

 very few about twice 

 this size that may be 

 foreign. There are also many forms barely I/a or 2/a thick, which 

 seem to be developmental stages of those mentioned above (fig. 44, 

 B, C) ; size, 7/t by 155/* to 10|ii by l75/i. Ectosomal spicules, tornotes 

 with ends microspined (fig. 44, A) \ size, 4/* by 145/x to 4/x by 155/a, 

 rare. First miscroscleres, anchorate chelas (fig. 44, Z>, F) ; length, 

 about 27/*, rare. Second microscleres, sigmas (fig. 44, E) ; length, 

 30/1 to 36/1, rare. 



Remarks. — This species is remarkable for the almost total loss of 

 all but the styles, and on them of the almost total loss of the char- 

 acteristic spination. The typical Myxllla structure is also almost lost. 

 On the other hand, all the items are there, though in reduced quan- 

 tity; a few characteristic dermal tornotes properly placed, a few 

 spines in the endospicules, a few^ characteristic anchorate chelas, a few 



Figure 44. — Myxilla agennes de Laubenfels : F, side 

 view of an anchorate chela, X 1,333; others, x300 



