ON FOSSIL SPONGES FROM METIS. 



37 



spicules form secondary aud tertiary structures within the larger areas lormed by 

 the primary spicules. 



Genus PROTOSPONGIA, Salter. 



1. — Protospongia tetranema, S.N. 



(Figs. 1 to 4. PI. Ill, figs. 1, 2.) 





Fic;. 1 . — ProUifpovgia lelnmcma. 

 A small specimen restored. 



Fin. 2. — Protofponffia tetranema. Anchoring 

 spicules slightly enlarged. 



In the specimens in which the outline of the sponge has been preserved, the body 

 appears to have been elongated oval or rounded, measuring about 46 mm. in length by 

 30 mm. in width. There was an aperture at the summit, though it cannot now be dis- 

 tinguished, except in a few rare instances. The wall of the sponge appears to have 



+ 



+ 



+ 



-h 



( / 



Fifi. o. — Proto/'pongia tetranema. Primary, secondaiy .'in<l 

 tertiary cruciform spicules, x 5. 



consisted — as in the other species of this genus — of a single layer of cruciform spicules 

 of various dimensions, disposed so as to form a framework with quadrate or oblong inter- 



' The characters of this and several of the following species were given in "Notes on Specimeos in the Peter 

 Redpath Museum, 188S." 



