66 Frederick Chapman : 



An antero-lateral crushing tooth occurs in one of the bores at an 

 horizon where fish reniaitis are abundant, and which may be rele- 

 gated to the top of the Janjukian. There is little doubt that it is 

 related to the specific form which has been previously recorded from 

 various localities in Victoria at or near the base of the Kalimnan. 

 The formerly recorded occurrences were nearly all represented by 

 the strong, broad lateral crushing teeth. The genus dates from 

 Upper Jurassic times (C falcifer, in the Solenhofen stone of 

 Bavaria). 



Occurrence. — Bore 8, 210-219 feet (Kalimnan or Janjukian). 



Fam. TRYGONIIDAE. 

 Genus TRYGON, Adanson. 



Trygok cf. rugosus, Probst sp. (Plate X., Figs. i)^a-d). 



Raia rugosus, Probst, (?) 1874, Beitrage zur Kenntniss der 

 fossilien Fische ous der Molasse von Baltringen, — Wurr- 

 temberg Naturw. Jahresheft 1874-82 (not seen). Zittel- 

 Barrois, 1893, Traite de Paleontologie, pt. i.. vol. iii., 

 pp. 102, 103, fig. 120a-c. Trygoii rugosus, Probst sp. 

 Eastman-Zittel, 1902, Text-book of Palaeontology, p. 42, 

 fig. 83. 

 Observations.-^— A single specimen of a well-preserved tooth with 

 bifurcated root was found in a sample of the Mallee bores contain- 

 ing an admixture of Kalimnan and Janjukian shells, but with a, 

 predominance of the latter fauna. Both in width and height the 

 tooth measures 4.25 mm. In the Miocene marls of Baltringen, 

 Wurtemberg, Probst found a similar pavement tooth, which he 

 referred to Baia, but which has since Ijeen placed in the genus 

 Trygon. Our specimen is in close agreement as regards both shape 

 and structure, so that it seems advisable for the present to refer it 

 tentatively to Probst's species, which came from a similar, or 

 nearly similar, formation. 



In respect to the generic position of the tooth, the marginal or 

 border teeth of the living Thornbacks (Baia), which I have been 

 able to examine in the National Museum through the kind offices of 

 Mr. J. A. Kershaw, show a bicuspid root, but differing from the 

 present specimen in having it more expansive or less hook-like than 

 in the Mallee fossil. 



Occurrence. — Bore 5, 163-175 feet (probably Janjukian). 



