201 
The following table of some of the specific characters of the two 
forms T. decipiens and T. quadribrachiatus is interesting: — 
Character of Stipes. 
Maximum width of stipes (2ud order) 
Width of stipes (1st order) 
Length of stipes {1st order) 
Length of sicula 
Length of nema ... 
Number of thecae in 10 mm. 
1 nclination 
Overlap 
Dimensions (length to width) 
T. decipiens. 
T. quadribrachiatus. 
Reclined straight. 
Horizontal straight. 
IV) 
2-(i 
•6 
;lo 
2-6 
2-3 
— 
5-0 
— 
11-9 
10-9 
27°-34° 
o 
o 
1 
O 
0 
1 2 
2 "S' 
^ 3 
4-6 times 
4 times 
‘‘ The presence of the prolonged virgula (nema), the much nar¬ 
rower thecae, and their smaller angle of inclination to the axis of the 
branch,’' states Dr. T. S. Halb, “ sufficiently distinguishes this species 
from T. quadribrachiatusd^ 
The essential morphological difference, however, is in the stipes being 
slightly reclined in T. decipiens and horizcntal in T. quadribrachiatus. 
That this is so is exemplified by fig. 64, an obverse aspect which wonld 
be otherwise impossible, also by other figures, especially that of a speci¬ 
men (pi. XXXIV., fig. 1a) collected by W. IT. Ferguson from Boolara, 
in which the thecae are preserved in relief. 
« 
Horizon and Localities .—Lower Ordovician and Upper Cambrian. 
The upper extent of its range is approximately equivalent to that 
of T. approximatus (vide p. 197 ante), but it appears much earlier than 
that species. At Lancefieid, W. J. Harris and the writer have found 
it associated very sparingly with Bryograptus victonce in beds which the 
later considers about the maximum development of the last-mentioned 
form. In this association only three identifiable forms were found, 
namely, B. victorice (very common), Clonograptus sp. (rare), T. deci¬ 
piens (rare). At the type locality Dr. T. S. HalP records Bryograptus 
victorice, B. clarhi, Leptograptus antiquus, Didymograptus pritchardi, 
D, taylori, Clonograptus flexilis, G. magniflcus, C. rigidus, C. rigidus 
var. tenellus, Dictyonema macgillivrayi and D. pidchellum. It would 
seem that this association is younger than that from the first-named 
locality, an inference somewhat supported by the stratigraphy of the 
locality. For other associations the reader is referred to the numerous 
reports on graptolites published in the Records of the Geological Sur¬ 
vey of Victoria. T. decipiens has been found at Lancefieid, Morning- 
ton, Boolara, Bromley, Tarnagulla, Llanelly, Inglewood, Eganstown, 
Wombat, Rock Lead, Dean, Barkstead, Bullarock, Clarendon, Elaine, 
Mansfield, &c., &c. 
' T. S. Hall, Proc. Koy. Soc. Viet. XI. 1899. 
2 Ibid, p. 168. 
® Ibid, p, 175, 
