VICTORIAN GRAPTOLITES. 
SOME SUB ZONAL FORMS OF THE LOWER BENDIGO AND UPPER 
LANCEFIELD ZONES. 
By R. A. Kehle, Assistant Field Geologist. 
Since Nicholson published his description of TetragrcDptus approxi- 
matus in 1873^ its origin, characteristics and affinities have never been 
discussed; in fact, outside of the graptolite shales of Victoria it appears 
to be a comparatively rare form, and, apart from the citations of its 
O'ccurrence at Point Levis^ and Arkansas^, the writer is aware of no 
others. First discovered in Victoria by W. H. Ferguson at Dromana, 
and recognised by the late Dr. T. S. Hall from there and many other 
localities, its constant recurrence, characteristic symmetry and range 
in regard to the well-authenticated Lancefield and Bendigo zones, invest 
it with importance as a subzonal species. Nicholson’s wood-cuts show 
few of the thecal characteristics, and his description was formulated at 
a time when the stipes of the first order (“funicle”) were considered 
to be destitute of thecae. In view of the light thrown on the genus 
Tetragraptus by recent research and the inaccessibility of Nicholson’s 
paper, it has been thought advisable to describe the Victorian form and 
compare it with the original description, particularly as it is likely to 
play a prominent part in the imminent subzoning of the Bendigo and 
Lancefield zones. 
Genus Tetragraptus, Salter. 
RECUMBENT DEPENDENT SERIES. 
Tetragraptus approximatus, Nicholson, Ann. and Mag. of Nat. PI is. 
4th Ser. Vol. XI. (1873), p. 136, fig. (Plate XXXIII.', Fig. 1a— c.) 
Tetragraptus approxiniatus, Gurley, Arkansas Geol. Surv. Ann. 
Rept., 1890. 
Tetragraptus approximatus, T. S. Hall, Reports on Graptolites 
from Balnarring and Bull-Dog Creek, near Dromana. Rec. Geol. Surv. 
Viet., vol. I., pt. 3, pp. 220-1. 
Tetragraptus approximaius, T. S. Hall, Report on Graptolites from 
Hustler’s Line of Reef, vol. I., pt. 4, p. 273. 
Tetragraptus approximatus, T. S. Hall, Reports on Graptolites at 
Inglewood. Rec. Geol. Surv. Viet., vol. III., pt. 2, pp. 195-6 (viz., 4032, 
4020, 3985, 3939). 
Fig. 61.—tetragraptus approxi¬ 
mates, NICHOLSON. 
Showing general aspect of polypary. 
Reverse vu w x 3L Bull Dog Creek, near 
Dromana. Collecied by W. H. Ferguson, 
Geol. Surv. Coll., No. 285. 
Description. —The sicula (or as much 
as may be seen) is about 1.1 mm. long, 
and has an inconspicuous nema. The 
first and second thecae appear to originate 
near the apex of the sicula and develop in 
opposite directions, initiating the stipes 
of the first order. The dichotomous divi¬ 
sion resulting in stipes of the second order 
takes place within the third and fourth 
thecae. The total length of the stipes of 
the first order is 2.5 mm. The stipes of 
the second order are slender (.5 mm.) 
at their commencement, but widen out in 
4 mm. to 2 mm., and maintain that width 
throughout. 
1 Ann. and Mag. of Nat. His. 4th Ser. Vol. XI. (1873), p. 136. 
* Ibid. 
» Gurley, R. R. The Geologic Age of the Graptolite Shales of Arkansas. 
Rept. 1890. 
Arkansas Geol. Surv. Ann. 
