166 Proceedings of the Royal Society of Victoria. 



forming an angle of 20° with the same ; free for one half their 

 length and indenting the branch about one half its width. 



I have much pleasure in dedicating this species to a former 

 pupil, Mr. George Clark, who was the first to find graptolites in 

 these, the oldest Australian graptolite beds yet discovered. 



Leptogpaptus, Lapworth, 1873. 



Leptograptus antiquus, n. sp. 



(PL XVII., Figs. 5, G). 



Polypary of extnniie tenuity. The two branches diverging 

 at about 180° from the sicula, and slightly curving with the 

 thecae on the concave side ; these primary branches at times 

 give off a secondary branch. Breadth of branches 0-1 mm. 

 Thecfe 7 in 10 mm., not in contact with one another; apertural 

 mai-gin straight or, when compressed in a different manner, 

 slightly concave ; inclined to the axis at an angle of 90°; outer 

 margin slightly concave and inclined at an angle of 30°. Breadth 

 from tip of theca to back of branch about 0-4 mm. 



Specimens giving off a secondary branch are not very common, 

 forms with only two branches being of far more usual occuri-ence. 

 The branching usually takes place in the neighbourhood of the 

 sicula and I have seen a few with four branches produced in 

 this way. In the example figui'ed the branch is given off at a 

 considerable distance from the sicula, it is well preserved and 

 there is no doubt as to the branching really taking place as 

 figured. 



Owing to the great delicacy of the polypary specimens 

 frequently occur in a somewhat tangled state, and in such 

 examples the sicula and first and second thecae are often moi-e 

 clearly preserved than the rest of the specimen. The species is 

 fairly common and is easily distinguished from Didymograptus 

 pritchardi n. sp. with which it is associated and with which it 

 is perhaps liable to be confused, by its more slender habit and 

 by the much more distant thecae which do not overlap. 



The genus has already been recorded from Lancefield by Mr. 

 G. B. Pritchard.i 



1 Proc. Roy. Soo. Vic, N.S. vii., 189,5, p. 30. 



