245 



b. Body tubulär, unbranched, closed at the extremity. 

 Euplectella aspergillum. 



c. Tubulär, branched; branches closed at their free extre- 

 mities, wall thick, formed of polyhedrally reticulated fibre. Possessing 

 a scopuline shaft. 



Aphrocallistes. 



d. Tubulär, branched; branches closed (?) at their free ex- 

 tremities; wall thin, formed of a single layer of rectangular lattice- 

 like fibre. Possessing a spino-capitate or umbrella-like headed shaft. 



Aulodictyon. 



e. Tubulär, branched; branches open and slightly expanded 

 at their extremities; wall very thin, only one layer thick. 



Farrea occa. 



f. The same: possessing both a scopuline and an umbrella- 

 like headed shaft. 



Farrea facunda. 



g. Infundibuliform; wall compounded of subrectangular 

 lattice-like, overrun by dendritic, branched, anastomosing fibre. 



Farrea infundibularis. 



h. Stalked, dichotomously branched; branches terminating 

 in oviform heads, each with a terminal aperture. 

 Sympagella. 



2. Spicules held together by amorphous sarcode. 



a. Sessile, vasiform, deeply excavated. 

 Asconema. 



b. Stalked, globet-shaped. 

 Crateromorpha. 



c. Sessile, sac-shaped. 

 Holtenia Pourtalesii. 



d. Oblong, excavated, provided with anchoring-spicules. 

 Rossella. 



e. Tubulär, unbranched, closed at the extremity. 

 Habrodictyon. 



f. Solid, not excavated, provided with anchoring-spicules 

 and a flesh-spicula, which is birotulate, 



Hyalonema. 



g. More or less globular, excavated, provided with ancho- 

 ring-spicules and characterised by birotulate flesh-spicule. 



Holtenia Carpenteri, Pheronema, Meyerina. 



h. Possessing the birotulate flesh-spicule in which the ter- 

 minations of both kinds of anchoring-spicules are known. 

 Labaria. 



3. Spicules held together in one part by vitrified fibre, and in 

 the other by amorphous sarcode. 



