DIAGNOSES OF THE SPECIES. 29o 



Discoliexaster, up to 100 n in dia.; leading down gradationally 

 to niicrodiscoliexasters of oO i'- dia., which are of niucli the «ame 

 appearance as the larger di«coliexaster ; terminals slender, with 

 disc composed of distinct prongs. 



Genus VITROLLULA I J. 



(See p. 37). 



V. fci'filis 1j, — Hniall, spindle-like or pouch-like ; may he 

 laterally com])ressed ; [irmly attached at base ; with small, simple- 

 edged osculum at the upper end, leading into deep gastral cavity. 

 External surface smooth ; internal surface without a gastral 

 layer over the apertures of excurrent canals. Parenchymalia consist 

 of slender diactins and of moderately large hexactins, the latter 

 being not uncommon. Uermalia, rough stauractins ; supported 

 by pentactinic hypodermalia. Gastralia, hexactins and pentactins; 

 s[)arsely present. Hexasters of two kinds : ( Jxyhexaster, 114- 

 140// in dianjeter ; each yhoil })rincipal with rather numerous, 

 slender, rough terminals ; never hexactinose or hemihexactinose. 

 ]Microdiscohexaster, l^ß-oO ii. in diameter, spherical; each principal 

 having numerous line terminals. 



Genus CRATEROMORPHA J. E. G KAY. 



(Diagnosis on p. 55). 



(\ ini'urri ,]. E. Gray. — Sponge-body smooth on the out- 

 side, the entire sponge l)eiug ex(]uisitely wine-glass- or tulip-like, 

 Parenchymalia mainly diactins, with isolated oxyhexactins. Amonu 

 the [)entactinic hypodermalia, diacttins may occasionally occur, 



