332 M. K. A. Zittel on Fossil Lithistidce. 



The genera Tretolopiay Adelopia^ PUohunia, Streblia^ Plio- 

 holia^ and PsilohoUa of Pomel, from the Miocene of Oran, 

 would come best here according to their external habit. 



Chonella, Zitt. 



Cwpulospongia p. p., D'Orb. 

 Chenendopora p. p., aiict. 

 Oculispongia p. p., Stellisjxmgia p. p., Rom. 

 Cujmiochonia, Dischonia p. p., From. 



Sponge irregularly funnel- or plate-shaped, simple or com- 

 pound, sometimes consisting of a contorted leaf, with a short 

 stem or thickened root. Both surfaces with small oval or 

 round pore-like apertures, from which straight or curved canals 

 run into the interior of the wall, which consists of a com- 

 plication of small, irregular filigreed and branched siliceous 

 corpuscles. The ends of these skeletal elements are often 

 united by a rather dense tissue of minute corpuscles of the 

 same form, but less pronged. In the wall and on the surface 

 there are many uniaxial spicules of variable form and size, 

 and, isolatedly, small anchors with their three flukes bent 

 backward. 



The type of the genus is Ciqjulospongia tenuis^ Rom., 

 beautiful specimens of which have been obtained from Linden 

 and Biwende. 



Chonella differs from the allied genus Seliscothon only by the 

 absence of a radial arrangement of the skeletal elements. By 

 the older writers most of the species were referred to Cujndo- 

 sponffta and Chenendopora, In external appearance Chonella 

 closely resembles Chenendopora^ Lamx. ; but the skeletal 

 structure is very different. In Ghenendopora the corpuscles 

 are much larger, less branched, and beset with wart-like blunt 

 tubercles, and the canals are stronger ; there is also a long 

 stem traversed by vertical canals. 



All the known species are Cretaceous. 



1. Cujmlosjyoiigia tenuis, Horn. Spongit. xvii. 7. Senonian. 



2. Achilleum auriformis, Horn. Kr. i. 3. Senonian, Peine. 



3. Cup)ulosp)ongia contorta,H6m. Spongit. xviii. 2. Ceno- 

 manian. 



4. Cupulospongia Eoemeri, Gein. Elbth. i. p. 29, v. 1-6. 

 Cenomanian. 



5. Chonella Geinitzi, Zitt. Cenomanian. 

 Stellisponffia planensis p, p., Geiii. Elbtli. p. 30, v. G-8 (uon vi. 1). 



Closely allied to Chonella are probably Pomel's genera 

 Cnemaulax, Sjpongoconia, Taseoco}tia, and Plioholiay from the 



