114 ART. 1. — I. IJIMA : HEXACTINELLTDA, 111. 



ROSSELLID.^. 



Lyssacine liexasterophora of cup-like or sacciform 

 body ; sometimes stalked ; generally firmly attached at 

 base and exceptionally rooted by tufts of basal spicules. 

 A few secondarily formed oscula may occur besides the 

 main terminal osculum. Dermal skeleton composed of 

 small dermalia with a variable number of rays and of 

 large hypodermalia . The latter are generally pent- 

 actins which often show a tendency to protrude out- 

 wards in such a way that the paratangentials form a 

 veil-like coverin o- over the dermal surface. The der- 

 malia, when hexactinic, have the distal ray not pinular 

 but much like the rest in appearance. The hexasters 

 are various but mainly oxyhexasters and discohexasters, 

 these generally occuring together; but sometimes one 

 kind occurs to the exclusion of the other. Oxyhexas- 

 ters are often hemihexactinose and hexactinose. Disc- 

 ohexasters frequently modified into discoctasters. 



Though this family has not formed a subject for treatment 

 in the present Contribution, the diagnosis is here given for the sake 

 of comparison with those of other lyssacine hexasterophorous 

 families. 



