ART. 12 



HEXACTINELLID SPONGES — OKADA 



The sieve plate is entirely lacking. The gastral chamber is very 

 shallow and small, measuring only 8 mm in depth. The root tuft 

 projecting from the basal surface is curled. The prostal marginalia 



Figure 1. — Pheronema ijimai, new species: a. Parenchymal hexactin, X 125; 

 b, hypodermal pentactin, X 125 ; c, dermal pentactinic pinule, X 250 ; d, 

 dermal i)entactinic pinule, X 250 ; e, young pentactinic pinule, X 250 ; 



• f. sastral pentactinic pinule, X 250 ; g, gastral pentactinic pinule, X 250 ; 

 h, mesampbidisk, X 250; i, micramphidisk, X 250; j, macramphidisk, 

 X 250 ; k, mesampbidisk, X 250 ; I, cuspidate, X 250 ; m, basalia, X 250 ; 

 n, macrouncinate, X 250 



are very inconspicuous. Specimen B, the smallest of all, has a nearly 

 egglike form and is 26 mm in breadth and 16.5 mm in height. The 

 circular osculum measures 2 mm in diameter. Specimen C repre- 

 sents an entire ball-like body, having at its apical end a nearly oval 



