416 Frederich Chapman: 



The pyritized (?) sponges now described resemble the Lithistid 

 types of the characteristic Upper Ctetaceous genus, Siphonia. 

 The material which has replaced these sponges is now in the 

 mineral form of marcasite. A radial structure in the interior is 

 visible through the cracks which have developed in one of the 

 specimens. On account of the complete crystalline replacement 

 of the mass of the sponge, no spicular structure is preserved. 

 As before stated, we have only the evidence of shape and super- 

 ficial characters on which to base conclusions. No sponge re- 

 mains appear to have been recorded from Australian Upper 

 Cretaceous rocks ; and the Lower Cretaceous has afforded only 

 one genus, in the Hexactinellida, viz., FurislpJionia. 



Description of the Specimens. 



cf. Genus Siphonia (Parkinson), Goldfuss pars. 

 Specimen A. (Plate LXXXIL, Figs. 1 a, h.) 



This specimen is apple-shaped, or, perhaps, more accurately, 

 melon-shaped. It is subspherical, but more elongated on the 

 vertical axis; very tumid in the zone of the basal third; de- 

 pressed and slightly tapering above the middle, where the sur- 

 face is tumulose. Upper surface rounded, with a relatively 

 small cloaca. Stalk inserted in a slightly depressed area. 

 Lateral surface of the body with irregular, anastomosing or 

 branching longitudinal grooves, giving the sponge the charac- 

 teristic rugose appearance often present in Siphonia. (1) Ves- 

 tiges of the fine incurrent openings may be seen on the surface 

 of the cast, and more thickly disposed in the depressed parts. 



Measurements.— Greatest length of body, 47.25 mm. 



Greatest width of body, 45 mm. 



Diameter of cloacal opening, circ. 4.5 mm. 



Length of peduncle, 4.75 mm. 



Width of peduncle at base, 8.75 mm. 



Remarks u/i specimen A. — The form of this pseudomorph may 

 be compared with that of the typieal Cenomanian species, 

 Siplionia tulipa, Zittel, wliirli is so comnion in the L^pper 

 Greensand of Warminster and Hlackdown, England. A critical 

 comparison shows the Queensland fossil to be nearest the 



