16 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 1 1 



There is a distinct surface layer 500 (x. thick, but this is nondetachable, 

 indicating a lack of extensive subdermal cavities. Occasional openings are 

 found which average about 1 mm in diameter. These are probably oscules. 

 The endosomal structure is decidedly firm and fleshy, and the gross 

 cavities cannot be seen with the naked eye. 



The chief spiculation consists of a mass of triacts, which have large 

 spines on the short ray ony. The triact is about 250 fi long and 25 /x thick. 

 The spined third ray averages 24 fi in length. The only other spicule type 

 is a very long, thin oxea. These are 4 /a thick and reach a length of 

 several mm. 



Holotype. — ^AHF no. 7. 



Type locality.— Cenos Island; Lat. 28° 05' 20'^ N, Long. 115° 18' 

 40'' S ; dredged from 20 fms in the bay. 



Distribution. — Same. 



Material examined. — 

 Sta. 287-34 Cerros Island 3-10-34 Shore 



Remarks. — It is interesting to note that Cyamon and Trikentrion 

 were found near each other in the Gulf of California. Cyamon is found in 

 the West Indies but not Trikentrion; both Trikentrion and Cyamon are 

 found in the East Indies. The California species of Cyamon, C. neon, is 

 similar to Trikentrion helium but has only very small spines on the triacts, 

 while this sponge has very large ones ; and, most important, the California 

 sponge has styles, while the Gulf specimen does not. Trikentrion flabelli- 

 formis has the large spines but also some monacts. It is probably the closest 

 relative of the new species. 



Family Myxillidae Hentschel 



Genus lOPHON (Gray) de Laubenfels 



lophon indentatus Wilson 



Plate 21, Figs. 41, 42; Plate 22, Fig. 43 



lophon lamella Wilson, 1904, p. 146. 

 lophon indentatus Wilson, 1904, p. 151. 



Diagnosis. — Specimens of this sponge are massive, brown in alcohol, 

 and mediocre in consistency. Oscules about 1 mm in diameter are scat- 

 tered over the surface of some specimens. No pores are evident to the 

 naked eye. The endosomal structure is "bready." 



The principal spicules are acanthostyles 13 /a to 17 /x by 300 /x to 333 //,. 

 The ectosomal spicules are smooth tylotes with heads microspined ; size 

 5 /i by 200 /x to 266 fi. Palmate anicochelas of the usual contort type about 

 13 ju, long, and bipocillates 15 )u, long are common in one of the specimens 



