THE SPONGES OF THE WEST-CENTRAL PACIFIC 127 



The ectosome presumably includes a cellular layer, or dermis, but this 

 is very inconspicuous. The endosome is densely filled with softly colloidal 

 material and shows no other striking characteristics. 



The skeleton consists of scattered spicules, not sharply divided into two 

 categories but nevertheless to be so interpreted. The strongyles, which are 

 about 3.5 p. by 225 p. to 6 p by 140 \x, are somewhat more numerous in the 

 outer region. The styles, which are about 5 p by 157 ju, to 8 /x by 170 \x, 

 are more characteristic of the deeper layers. The microscleres are quite 

 noteworthy. They are amphidiscs, or birotules, 12 /a in length, but of ex- 

 ceedingly thin shaft dimensions. The latter is definitely less than 1 p 

 thick. The heads also are small, only about 2 ju, or 3 /a in diameter; and, 

 partly because of the small size, teeth or clads cannot readily be discerned 

 at their edges. 



This species may be compared to baculifera, from which it differs in 

 being black and smooth where baculifera is purple and conulose ; and, in 

 addition, there is the considerable difference in shape of the microscleres. 



The specific name is derived from a Greek word for a bit of bread 

 permeated by gravy or soup and refers to the very colloidal condition of 

 this sponge. 



GENUS IOTROCHOPSAMMA, new 



In 1906, page 482, Whitelegge described a sponge as Iotrochota arbuscula 

 from Australia. Instead of black or purple, as most related sponges are, it 

 was described as gray. It was ramose and contained microscleres 20 fi long 

 and in many respects was typical of either Iotrochota or Hiattrochota. Other 

 than these birotulate microscleres, however, no spicules were found. Instead, 

 a considerable quantity of sand and other foreign material was present in 

 the skeleton of this sponge. This constitutes such a great difference from 

 other genera that it is considered worthy of being elevated to full generic 

 rank. Iotrochopsamma has as type, and for the present as its only species, 

 arbuscula, and may be defined as having a principal skeleton of sand ac- 

 companied by birotulate microscleres. The family allocation is puzzling. 

 Because of the foreign material it would appear to belong in the family 

 Psammascidae, but the obvious close relationship to Iotrochota and Hiattro- 

 chota is such that for the present it is left, with apologies, in the Myxillidae. 



FAMILY TEDANIIDAE Ridley and Dendy 



GENUS TEDANIA Gray 



Tedania oligostyla, new 



Text Figure No. 80 



This species is here represented by the following : 

 U.S.N.M. No. 22970, My No. M. 346, collected July 5, 1949, by hand while 



