M. K, A. Zittel on Fossil Lithistidce. 385 



tionably substantiated to distinguish the Jurassic and Silurian 

 genus Eryon from the recent Polychehs is that in the latter, 

 but not in the former, the inner antennse are furnished with a 

 scale on the inner margin. This is a point to which attention 

 has not been previously directed ; but I think it affords suffi- 

 cient ground for keeping the genera distinct. 



With respect to the chelation (as in Pentacheles) of the last 

 pereiopods in Eryon^ Dr. Woodward writes to me : — " The 

 hind foot seems to be simple, not chelate — as far as the speci- 

 mens before me enable me to form an opinion, certainly. I 

 thought I detected an indication of the last foot being chelate 

 [minutely so) in a Solenhofen Eryon ; but it might be due to 

 fossilization." 



XLIII. — Studies on Fossil Sjponges. — II. Lithistidce. 

 By Karl Alfred Zittel. 



[Continued from p. 341.] 

 Rhizomorina [continued). 



POMELIA, Zitt. 



[Recent.) Sponge from clavate to- cylindrical, short-stalked, 

 attached by a broad base. Vertex convex, with a pit-like 

 depression, in which there are several small circular apertures 

 of vertical tubes which traverse the sponge-body. Isolated 

 pits of the same kind with tubular canals on the sides. Sur- 

 face very regularly furnished with fine pores. Skeleton 

 formed of short, curved, rather thick, branched corpuscles, 

 covered all over with processes, arranged in trains, the forked 

 ends of the branches being closely interwoven. Corpuscles 

 at the surface of the same form as those -of the interior, but 

 no true surface-structures present in the specimen. 



The genus, which is named after M. Pomel, is very nearly 

 related in external appearance to various sponges from Oran 

 referred by Pomel to Jerea, Polyjerea, Marisca, and Jereopsis, 

 some of Avhicli probably approach this genus more nearly 

 than the Cretaceous forms of Jerea and Jereica. The sponge 

 described is from Florida, and was received from Prof. 0. 

 Schmidt under the name of CoraUistes ? polydiscus. 



Jereica, Zitt. 



Jerea p. p., auct. ; Polyjerea p. p., auct. 

 Spumispongia p. p., Quenst. 



Sponge simple or compound, cylindrical, top-shaped, clavate, 

 Ann. & May. N. Hist. Ser. 5. Vol. ii. 2G 



