[DAWSON] FOSSIL SPONGES AND OTHER ORGANIC REMAINS 



lOl 



Order SILICEA. 



Suborder Hexactinellida. 



Group Lysmkina. 



Family Protospongid^e, Hinde. 



Genus PEOTOSPONGIA, Salter. 



This genus was estahlislied by the late Mr. Salter from some remains 

 of lattice-like spieular bodie.^ found in the ]\[iddle Camln-ian of Wales, and 

 which, though fragmentary and obscure, that eminent naturalist was 

 able to refer to the group of Siliceous sponges. The genus includes sevei-al 

 of the Metis species, which have enabled us to complete the characters of 



Salter's genus. 



1. — PROTOSPONOrA TETRANEJIA. DawsOH.' 



(Figs. 1 to 5. PI. 1., Figs. 1 and 4.) 



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Fic l.—Proloaponffiti tefrancmn. 

 A small .specimen restored. 



Fi(i. 2.—Profospon!/ia fetrnnenia. Anchor- 

 ing-spicules slightly enlarged. 



In the specimens in which the outline of the sponge has been pi-e- 

 served, the body appeai-s to have been rounded or broadly oval. There 

 was an aperture or osculum at the summit, though it can be distin- 

 guished only in a few sjjecimens. The wall of the sponge appears to have 

 consisted— us in the other species of this genus— (tf a single laj-er of 

 cruciform spicules of various dimensions, disposed so as to form a frame- 

 work of quai':.itc or oblong interspaces. The i-ays of the larger spicules 

 constitute the boundaries of the larger squares ; but owing to decay 



• The characters of this and several of the following species were given in " Notes 

 on Specimens in the Peter Redpath Museum, " and in the Transactions of the Royal 

 Society, 1889. 



