70 



COELENTERATA— PORIFERA 



PHYLÜM II 



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

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

 common in Trias, Jurassic, and Cretaceous. 



Fig. 85. 



Peronidella cylin- 

 drica (Münst.). 

 Upper Jura. ; Miig- 

 gendorf. x 1/2. 



Fio. 86. 



Peronidella diimosa (From.). 

 Hils ; Berklingen, Bruns- 

 wick. Natural size. 



Fig. 87. 



Corynella quenstedti Zitt. Coral-Rag; Natt- 

 heim. 0, Sponge, natural size ; b, Skeletal 

 fibres, 4/1. 



Fig. 88. 



Eusiphonella bronni 

 (Münst.). Coral-Rag ; 

 Nattheim. Natural 

 size. 



Oculospongia tu- 

 hulifera (Goldf.). 

 Kreidetuflf; Mae- 

 stricht. 

 size. 



Fig. 90. 



Eusiphonella 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 vertical rows. 

 External surface per- 

 forate. Upper Jurassic. 

 Corynella Zitt. (Fig. 

 87). Knob-like, cylindri- 

 cal, or top-shaped, thick- 

 walled, simple, or com- 



Natural (Q^eSr €0?^^ P^'^*®' ^^^^^^ ^^^^^^ " 



Nattheim. Natural size. shaped, shallow, terminat- 

 ing below ^in a series of 

 vertical branching tubes ; exhalent aperture often surrounded with radially 

 diverging furrows. Ostia 

 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- 

 posite 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 



Hils 



Fig. 91. 



Elasmostoma acntimargo Roem. 

 Berklingen, Brunswick. 



Fig. 92. 



RhapMdo nema farringdonense 



(Sharpe). Lower Cretaceous 



(Aptian) ; Farringdon, Berkshire. 

 2/0 natural size. 



