LETJCANBBA. — EUPLECTELLA. 19 



Spongia injlatn, Delle Chiaje, Memoire sulla storia e anatomia degli aniraali 

 senza vertebrale, Napoli, vol. iii. p. 114 (1828). 



Sycimda aspera, E. Haeckel, " Prodromus eiues Systems der Kallcscbwamme," 

 Jenaische Zeitschrift fiir Medizin und IS'aturwissenschaften, Band v. 

 Heft ii. Seite 242, spec. 60 (1870). 



Sycinula aspera, O. Schmidt, Die Spougieu des Adriatisclien Meeres, iii. Sup- 

 plement, Seite 35 (1868). 



Sycon aspernm, 0. Schmidt, Die Spongien des Adi'iatischen Meeres, Seite 15 

 (1862). 



Geographical Distribution. — Mediterranean. 



2. Classis SI LICE A. 



Mesoclermalia with a siliceous or horny skeleton, or without 

 any skeleton. 



1. Ordo HEXACTINELLIDA. 



Silicea with very loose soft parts, and with spicules which are 

 either isolated or united to form a continuous framework, and 

 belong or are reducible to the triaxial system. 



Subordo LYSSACINA. 



Hexactinellida in which the spicules either remain altogether 

 isolated, or are in part subsequently and irregularly united by 

 transverse synapticula. 



Familia EUPLECTELLID^. 



Lyssacina with hexasters ; chambers isolated and thimble- 

 shaped. The dermal skeleton contains dermal sword-shaped 

 oxyhexacts with long proximal ray. 



Genus EUPLECTELLA. 

 EnplectellidjE with parenchymal oxyhexasters. 



