JEREA. 71 



In the shallow depression at*the summit of the sponge are the apertures of a group 

 of canals, about 1 mm. each in width. From the summit there extends over the 

 surface a series of canals which apparently anastomose with each other, and give a 

 reticulate appearance to the sponge. In a vertical median section the only canals 

 distinctly shown extend in an arched direction from the surface to the centre of the 

 sponge. These canals appear to be very wide near the outer surface, and to open 

 directly into the reticulate canals. The interspaces of the surface between the 

 reticulations appear to have no other apertures beyond the openings of the spicular 

 mesh. 



The interior skeleton is built up of robust spicules with smooth arms and prominent 

 botryoidal nodes at their junction with each other. No dermal layer has been 

 preserved. 



This species may be recognized by the reticulated surface and the peculiar character 

 of the canals extending from it to the centre of the sponge. 



Bistrihution. Upper Green Sand : Warminster, Blackdown ; Cap la Heve ; Retsel, 

 Ardennes. Craie Chloritee : Honfleur, Vaches Noires. Gault \ near Folkestone. 



Jerea Quenstedti, Zittel. 



1878. Jerea Quenstedti, Zitt. Studieu, II Ab. p. 81, t. 10. f. 2. 

 1878. Slphoniaficus, Quenst. Petref. Bd. 5, p. 431, t. 135. f. 20-33. 



Microscopic slides with spicules of this species. 

 Distribution. Quadraten-Kreide : Linden, Hanover. 



Jerea cordiformis, Ilinde, n. sp. (Plate XV. figs. 3, 3 a.) 



Sponge obcordate in form, with an evenly rounded summit, constricted at the base, 

 and apparently supported on a stout stem. The only specimen in the collection is 

 93 mm. in height and 73 mm. in width. 



The somewhat elongated rounded ridge at the summit is pierced by numerous 

 apertures of the vertical series of canals, 2 mm. in width. From the summit also, 

 open, sinuous, branched canals extend down the sides of the sponge. The canals 

 extending from the surface towards the interior are greatly arclied, and 1 ram. in 

 width. 



As is usual in all the specimens from the Grey Chalk, no spicules have been 

 preserved in this form, but prominent junction-nodes can be recognized ; and I have 

 no doubt that the sponge belongs to the Tetracladina family. 



In its peculiar form and in the character of the summit this sponge is distinct from 

 any hitherto referred to this genus. 



Distribution. Grey Chalk : near Dover, 



