RELATIONSHIPS OF THE AUSTRALIAN CAINOZOIC SYSTEM. 
as to age; for it has been identified by Mr. Robt. Etheridge as 
Trigona semi-undulata, of the type-form which is only found 
in the Janjukian series in Victoria, in being ornamented with 
fimbriated ruge instead of almost plain sulcations as in the 
Balcombian varicty.* In the last boring in the Mallee which 
I have examined (No. 11), there are 333 feet of white polyzoal 
limestone with occasional black cherty bands, and the bottom of 
the series was not reached. The fauna altogether showed a strong 
Aldingan and Batesfordian aspect ; both Aldinga (lower beds) and 
the Batesford Limestone being of Janjukian age. To the westward 
these bores showed a thinning-out of the deep water polyzoal facies, 
the strata being replaced by terrigenous greensands with a rich 
fish fauna. The Janjukian polyzoal limestone and greensands pass 
upwards by gradual sequence into Kalimnan (Lower Pliocene) shell 
marls and sands of a decided littoral aspect. The maximum thick- 
ness of this Kalimnan series is 92 feet. These are followed by 
estuarine foraminiferal sands, which I regard as Werrikooian 
(Upper Pliocene), similar in age to the upper beds of the 
Glenelg River. The maximum of these deposits is 163. feet. 
Pleistocene beds are indicated by barren quartz sands and grits. 
The later Pleistocene and Holocene stages are represented by 
ferrugimous sands, and pinkish concretionary limestone, with 
occasional land-shells; this series attaining a maximum. thick- 
ness of 148 feet. A full report on the bores of the Mallee district, 
Victoria, is being prepared at the National Museum, and will be 
published shortly. 
Another but smaller sub-artesian basin, or gulf of the Janjukian 
sea—really the remanet of a once very extensive area—is seen in 
the Eucla Basin, north of the Great Bight, and underlying the 
Nullarbor (= treeless) Plains. The absence of running water in this 
locality is due to the porous character of the white polyzoal limestone ; 
any moisture falling upon its surface being absorbed as by a sponge, 
to be carried away by means of underground streams. The average 
height of the Bunda Plateau, as this country round the Great Bight 
is called, is from 800 to 1,000 feet. 
The limestone country of the southern part of Western Australia 
is of great thickness, since, according to Mr. H. Deane (in a lecture 
before the Royal Society of Victoria in 1911), a Government 
bore passed through 1,370 feet of limestone before reaching 
bed-rock. From the description it appears to be a similar lime- 
stone to that of the Eucla Basin. It is to be hoped that some 
data will be gleaned in the near future from borings and well- 
sinkings in this area during the construction of the Transcontinental 
Railway. 
* Trigoma semiundulata, var. lutosa, Pritchard, Proc. R. Soc. Vict., vol. xv. (N.S.), pt. 1, 
1902, p. 92, pl. xv., figs. 6, 7. 
14328.—D [ 49 | 
