Art. VII. — On Tvjo New Fossil Sponrjes from Sandhurst. 



By T. 8. Hall, M.A. 



(Communicated by A. Dendy, M. !Sc., F.L.S.) 



[Bead July 12, 1888.] 



Both the specimens, figures of which I append, were found 

 at Iron bark, Sandhurst, Victoria, in rock of the Landeilo 

 flag age. The spicules are of a dead black colour, and are 

 preserved in a soft, cream-coloured, slightly micaceous 

 schist. 



Genus. — Protospongia. Fam. — Protospongida; (Hinde). 

 Sub-Order. — Hexactinellida^. 



Hinde defines Protospongia as follows: — "Form of sponge 

 unknown. The portions preserved consist either of detached 

 spicules, or fragments of a delicate spicular framework, 

 formed of a single layer of four-rayed spicules of various 

 dimensions. The larger spicules are arranged so as to form 

 regular squares, which are divided by smaller spicules into 

 smaller squares, and these are again sub-divided, so that the 

 surface of a fairly complete specimen resembles lattice-work." 



Protospongia Reticulata (n. sr. Figs. 1 and 2). 



Description. — The specimen is nearly circular in outline, 

 and probably in its living state had a somewhat spherical 

 form. Its length is about 7 cm. and its width about G cm. 

 The spicules are crucifonn, the four rays crossing at angles 

 varying from 70" to 90°, the variation from the usual 

 rectangular form of Hexactinellid .spicules being probably 

 due to compression. The spicules are of various sizes. The 

 larger ones (the rays of which measure 3'5 mm. in length 

 and o mm. in diameter) are so placed that they enclose 

 squares, and smaller spicules, the rays of which measure 

 1'5 mm. in length, are placed inside these larger squares so 

 as to divide each into four smaller squares. Numerous 

 smaller cruciform spicules are scattered about in an 

 apparently irregular manner, and it does not appear that the 

 subdivision of the squares is carried as far as in ty[)ical 



