1886.] POSITION AND CLASSIFICATION OF SPONGES. 579 



3. Familia Rossellid^, F. E. Schulze. 



The dermalia have uo centripetal ray. 



Lanuginella, O. Schmidt ; Polyhphus, F. E. Schulze ; Rossella, 

 Carter ; Acanihascus, Batkydorus, Rhabdocalyptus, Crateromorpha, 

 Aulochone, Caulocalyx, and Aulocalyx, F. E. Schulze. 



ii. Tx^hvii Amp hidiscophor a, F, E, Schulze. 



Amphidiscs in the limiting membranes. Hexaster absent in the 

 interior. A basal tuft is always present. The ciliated chambers 

 appear as somewhat irregular sac-shaped extensions of the membrana 

 reticularis. 



4. Familia Hyalonematid^, Gray. 



Numerous pentact pinnulse in the dermal and gastral surfaces. 



1. Subfamilia Hyalonematince, F. E. Schulze. 



Calyculate, with a well defined oscula-area on the upper surface. 

 Hyalonema, Gray; Stylocalyx, F. E. Schulze; Pheronema, Leidy ; 

 and Poliopoffon, Wyville Thomson. 



2. Subfamilia Semperellince, F. E. Schulze. 



Without gastral cavity and terminal oscula-area, with root-tuft. 

 Semper ella, Gray. 



To this Subordo the fossil families Receptaculitidse and Monakidse 

 belong. 



II. Subordo DiCTYON iNA, Zittel. 



The parenchymal hexacts early coalesce in a regular manner, so 

 as to form a firm skeleton. 



i. Tribus Uncinataria, F. E. Schulze. 



With uncinates. 



i. Subtribus Clavularia, F. E. Schulze. 



With radially situated clavulae. 



1. Familia FARREiDiE, F. E. Schulze. 



The skeleton forms a single layer; from the joining points conical 

 extensions arise, in a direction vertical to the surface of the network. 

 Farrea, Bowerbank. 



2. Subtribus S copula r i a, F. E. Schulze. 

 With radially situated scopulae. 



2. Familia Euretid^, F. E. Schulze. 



Branched and anastomosing tubes. The skeleton-net forms several 

 layers. 



Eurete, Carter ; Periphragella, Marshall; and Lefroyella, Wyville 

 Thomson. 



38* 



