GRAPTOLITES OP VICTORIA. 
oldest known representative of this characteristic group of 
dependent Didymograpti. 
D. mendicus differs from D. bidens in the more abrupt 
proximal curvature of its branches ; in its distally wider angle 
of divergence ; in its greater distal width ; and in its more 
closely set thecae. It has, however, the characteristic small 
overlap, the same ratio of thecal length to breadth, and unusually 
long first thecae. Unquestionably D. mendicus is the Australian 
equivalent of the New Zealand form, D. bidens , and it is asso- 
ciated with a similar graptolite fauna. 
Associated graptolites . - Didymograptus protobifidus Elies, Telragraptus 
quadribrachiatus (J. Hall), T. similis (J. Hall), Phyllograptus spp., etc. 
Horizon . — Lower Ordovician, Castlemaine Series, Zone C5 or C4. 
Locality. — Connell’s Mine, east bank of Werribee River, 12 miles south of 
Daylesford. 
Genus TETRAGRAPTUS Salter 1863. 
Tetragraptus chapmani, sp. nov. 
(Plate XX, figs. 3 a, 3b) 
The obverse view is the only one so far seen. Sicula 1.2 mm. long, 0.7 mm. 
wide. Theca l 1 originates suborally, apparently a little below aperture of 
sicula ; theca l 3 crosses a little above l 1 and lies slightly downwards across 
sicular aperture. Funicle apparently straight ; consists of three pairs of 
thecae (l 1 , l 2 , 2 1 , 2 2 , 3 1 and 3 2 ) ; 7.7 mm. long. Thecae 3 1 and 3 2 bifurcate 
and give rise to four slender branches of second order uniformly under 0.5 mm. 
wide. Secondary branches long (in one case 96 mm.), sinuous, irregular in 
direction. Thecae 9 to 11 in 10 mm. ; between two and three times as long 
as wide ; overlap one-fourth or less of length ; ventral margins inclined 
between 20° and 25°, apertural margins at 70° to axis of branch ; both slightly 
concave. 
Remarks. — The thecae appear to be simple tubes, not unlike 
those of some Bryograpti, but more specialised. Their apertures 
come into view in rotation as if the thecae were arranged 
spirally ; this is perhaps due to torsion of the branches. 
Specimens seldom have more than one thecae at a time laterally 
compressed, and this makes the study of thecal structure 
difficult, even in specimens in partial relief. 
The angle between each pair of branches of the second 
order at the end of the funicle varies considerably and is of no 
specific importance. 
We regard T. chapmani as one of the most important and 
characteristic of Victorian graptolites ; in fact we are not aware 
of any other member of the Dichograptidae with such peculiar 
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