70 



COELENTERATA— PORIFERA 



PHYLUM II 



absent. The coarse, anastomosing skeletal fibres composed of closely packed 

 three-rayed and one-rayed spicules. Sparse in Devonian (P. constrida Sandb.) ; 

 common in Trias, Jurassic, and Cretaceous. 



Fig. 85. 



Peronidella cylin- 

 drica (Miinst.). 

 Upper Jura. ; Miig- 

 gendorf. x i/o. 



Fig. 86. 



Peronidella dvmosa (From.). 

 Hils ; Berklingeii, Bruns- 

 wick. Natural .size. 





Fig. 87. 



Corynella quensiedti Zitt. Coral - Rag ; Natt- 

 heiin. o, Sponge, natural size ; h, Skeletal 

 fibres, 4/i. 



EusiphoneUa Zitt. (Fig. 88). Similar to preceding, but thin-walled, with 



broad cloaca extending to 

 the base, into which con- 

 duct radial canals ar- 

 ranged in vei'tical rows. 

 External surface per- 

 forate. Upper Jurassic. 



Corynella Zitt, (Fig, 

 87), Knob-like, cylindri- 

 cal, or top-shaped, thick- 

 walled, simple, or com- 

 posite. Cloaca funnel - 

 shaped, shallow, terminat- 

 ing below (in a series of 



vertical branching tubes ; exhalent aperture often surrounded with radially 



diverging furrows. Ostia 



EusiphoneUa hronni 

 (Miinst.). Coral-Rag ; 

 Natthelm. Natural 

 size. 



Oculospongia tu- 

 hulifem (Goldf.). 

 Kreidetuff ; Mae- 

 stricht. Natural 

 size. 



Fig. 90. 



Stellisponyia glomerata 

 (Quenst.). Coral - Rag ; 

 Nattheim. Natural size. 



conducting 



into 





numer- 

 ously branching radial 

 canals, which unite again 

 in larger excurrent canals, 

 and open into the cloaca. 

 Common in Trias, Jur- 

 assic, and Cretaceous. 



Stellispongia d'Orb, 

 (Fig, 90). Usually com- 

 j)osite stocks made up of 

 hemispherical, or short 



pear-shaped persons, with Upper surface, natural size 



base enveloped by com- 

 pact dermal layer. Summit dome-shaped, with shallow cloaca surrounded by 

 radial furrows ; radial and vertical canals terminating along sides and basis of 



Fig. 01. 



Elasmostoma acatirnaiyo Roem. 

 Hils ; Berkliugeu, Brunswick. 



Fig. 92, 



Ehaphido neina farringdonense 

 (Sliarpe). Lower Cretaceous 



(Aptian) ; Farringdon, Berkshire. 

 2/3 natural size. 



