32 ART. 9. — I. IJIMA : HEXACTINELLTDA. 



longitudinally and transversely (always ?). Sieve-plate present (?). 

 Skeletal beams unfused in the upper part of the body. The 

 strongest prineipalia parenehymalia are mostly stauractins. Disc- 

 ohexaster predominantly in the ordinary hexaster form ; some- 

 times hexactinosc ; diameter about 170//. Floricome about 100/* 



in diameter. 



« 



Genus Heterotella Gray. 



With a single species. 



Heterotella corblcula (Bowerb.). — Corbitellinse of saccular 

 shape, the lateral wall slightly closing in towards the margin of 

 a, flatly convex sieve-plate. With numerous, round, irregularly 

 arranged parietal oscula. Skeletal beams unfused. Prineipalia 

 parenehymalia diactins ; accessoria diactins and hexactins. Micro- 

 hcxactins present, in which the rays are sparingly supplied with 

 long, slender spines ; such a. ray sometimes appearing like a long 

 oxyhexaster-principal with 1-3 terminals. Floricome and gra- 

 phiocome only present ; no discohexaster. 



