68 
GRAPTOLITES OF AUSTRALIA 
exhausts the interesting features presented by the present 
collections.” 
“Apart from the forms which may be called abnormal the 
most interesting feature of the B5 assemblage from Allot. 
16A is the notable ‘burst’ of extensiform Didymograpti and, 
contrary to the conclusions drawn by Elles^ from English 
collections, the commonest forms on this, the lowest Victorian 
horizon on which Didymograpti are common, are those with 
‘closed’ proximal regions. In Victoria the only Didymo- 
grapti of the Upper Lancefieldian are the distinctive D. 
taylori and D. pritchardi. The horizontal forms which come 
in so suddenly in B5 persist to higher horizons, but the D. 
hirundo type does not range above B4 where it reaches its 
climax in D. kitus var. acqiialis nov.” 
“The B5 horizon corresponds with that of the reclined 
Tetragrapti of tlie zone of D. extensus as defined by Elies and 
this agrees with her earlier correlation. The same horizon 
has been noted in New Zealand but there, as at most localities 
in Victoria, the number of species seems limited and there 
is no indication of the ‘burst’ of horizontal Didymograpti. 
The lower Bendigonian ‘burst’ of new forms is preceded by 
the ‘burst’ of Bryograpti and Clonograpti in the Middle 
Lancefieldian (L3) desciibed by T. S. Hall. In the LI beds 
the incoming of the horizontal Tetragrapti such as Tetra- 
g rapt us approxim at iis and T. accHna ns does not alter the 
general asjiect of the assemblage, but the entry of the depen- 
dent Tetragrapti such as T. fruticosus and the extensiform 
Didymograpti in B5 introduces important new elements. A 
comparison of the Lower Bendigonian with those assemblages 
from other countries which may be correlated best with that 
stage shows that local differences are probably more impor- 
tant than some European graptolithologists have been pre- 
pared to admit, and that schemes of development based on 
the appearances of forms in any one region may not stand 
the test of observation when applied to more distant fields.” 
Commenting on branching as a generic character of the 
Dichograptids, they stated that “the presence of so many 
Dichograptid forms with apparently transitional numbers 
of branches brings forcibly to notice the artificial distinctions 
such as divide Loganograptus and Dichograptiis, Trocho- 
graptus and Schisograptus and even Tetragraptus (where 
three-branched forms have been included in a genus which 
by its name was meant for four-branched forms). . . . The 
1. Elies, G. L. Summary of Progress, Geol. Surv. G. Brit, for 1932, 
II, 1932. 
