Fossil Sponges. 127 



features of the canal system, but the spicular structure is now Sponges, 

 scarcely recognizable. (Fig. 178.) GALLEBY 



X. 

 West Side. 



Wall-caEet 



7&8, 



Table- 



cases 



11-15. 



Fig. 178. — Verruculina Eeussii, M'Coy. Upper Chalk: Flamborough Head. 

 (Reduced to one-third.) 



The principal Lithistid genera in the Upper Chalk are Seliscothon, Table- 

 Verrueulina (Fig. 178), Stichophyma, Jereica, Scytalia, Pachinion, ^ 412 

 Doryderma, Seterostinia, Isorhaphiniay Phymatella, Callopegma, Wall- 

 Siphonia, Thamnospongiay Plinthosella, and Phymaplectia. The 

 Hexactinellid genera comprise Craticularia, Leptophragma, CoscinO' 

 pora, Guettardia, Ventriculites (Fig. 179), Polyhlastidium, Cephalites, 



Fig. 119.— Ventriculites infundibuliformis, S. Woodw., a Hexactinellid sponge, 

 reduced from Cat. Foss. Sponges, pi. xxvi. Upper Chalk. 



Plocoscyphia, Camerospongia, Callodictijon, and Cceloptychium. 

 Tetractinellid sponges are represented by Pachastrella and Stelletta, 

 and by numerous detached trifid spicules of Geodia (?). Monacti- 

 nellid sponges include boring forms of Cliona. The Calcisponges 

 are not very numerous ; they belong principally to Elasmostoma and 

 Pharetrospongia. 



Among the more striking examples of the Upper Chalk sponges 



