170 F. Chapman: 



The occurrence of this fossil confervoid is of especial interest 

 on account of the rarity of fossil remains of this character. Im- 

 pressions of confervoid-like structures in rocks were named Con- 

 fervites by Brongniart in 1828. 



Bornemann also described a Cambrian fossil from Sardinia, 

 to which he gave the name of Confcrvitcs chantransioides ; the 

 filaments of this fossil have a diameter of 6-7 /x.^ 



Dr. C. D. Walcott has lately described a genus of algae, Mar- 

 polia,^ from the Middle Cambrian shale of the Burgess Pass 

 Quarry, British Columbia. This form closely resembles the habit 

 of growth in Cladophora, though no actual structure of the 

 thallus was determinable. It is relatively larger in size than the 

 form here described from the opal. Dr. Walcott refers the 

 genus Marpolia to the Cyanophyceae, but a comparison is made 

 with Cladophora (Chlorophyceae). 



Some forms of the Codiaceae are also filamentous and branch- 

 ing, and are not unknown in fossil deposits, but these appear to 

 be of marine habitat. 



Age. — Late Cainozoic; probably Pleistocene. 



Description of Spicules in Opal (Fig. 2). 



The majority of the spicules found in one specimen examined 

 are of the typical Spongilla type, being straight, curved or slender 

 fusiform; some are nearly cylindrical and pointed at the ex- 

 tremities, whilst others are arcuate and much thicker in the 

 middle. A few extremely slender needle-like forms are present. 

 The surfaces are apparently all more or less spinulose. These 

 appear to belong to the genus Spongilla, whilst a few smooth 

 forms may belong to Meyenia. Very few traces of amphidiscs 

 occur, but those seen are of the type of Spongilla capewelli, a 

 species named by Bowerbank from specimens occurring at Lake 

 Hindmarsh, Victoria. ^^ A portion of what appears to be the 

 liead of a birotulate spicule, with a denticulate margin shows 

 5ome resemblance to the form described by Prof. Haswell as 

 Meyenia ramsayi}^ 



Regarding a similar diatomaceous and sponge spicular deposit, 

 from the Warrumbungle Mountains, Mr. R. Etheridge (junr.) 



8. Kals. Leop.-Carol Deutsche Akad. Naturforscher, vol. LI., 1887. 



9. Smithsonian Misc. Coll. vol. LXVII., No. 5. 1919 p. 233. 



10. Proc. Zool. Sbc. Lond., 1863, p. 447, pi. XXXVIII.. lig. 3. 



11. Proc. Linn. Soc. N.S. Wales, vol. VII.. 1883, p. 210. 



