410 Transactions. 



Art. XL1V. — On the Occurrence of Lower Ordovician Graptolites in Western 



Otago. 



By T. S. Hall, M.A., D.Sc., University of Melbourne. 

 Communicated by Professor P. Marshall, M.A., D.Sc, Otago University. 



[Read before the Otago Institute, 5th December, 1911.] 

 Plate VII'. 



Through the kindness of Professor P. Marshall, of Dunedin, I have had 

 the opportunity of examining half a dozen small slabs of graptolite-bearing 

 shales collected by Mr. J. S. Nicol, of Gore, at Preservation Inlet, at the 

 extreme south-west corner of New Zealand. 



The rocks containing the fossils are of two kinds. Both are dark blue 

 in colour. One is slightly micaceous, and has small white spots of some 

 decomposed mineral in it. It has a somewhat irregular fracture. .The 

 other rock is of a darker tint, being almost black, and splits more freely 

 along the bedding-plane. Both rocks are silicified. The graptolites are 

 mostly very distinctly shown, being preserved in a silvery-white mineral 

 which is generally spoken of as gumbelite. Further examination should 

 result in the discovery of a larger supply of better material than has been 

 submitted to me. 



The fossils clearly belong to the series known as Lancefieldian in Victoria, 

 which is very low down in the Ordovician, and contains some forms which 

 elsewhere are of Cambrian age. One of the most striking features is the 

 exact resemblance of the darker rock to that which occurs at Lancefield 

 itself. The slabs containing the specimens shown in figs. 1 and 2 may be 

 matched both lithologically and palaeontologically with examples from the 

 Victorian locality, twelve hundred miles away. That both should be similarly 

 silicified is very remarkable. 



I have ventured on two specific identifications only, with a separate 

 variety in one case. But besides these several examples are shown of another 

 genus, Bryograptus, which may be new, and probably are, but as the thecal 

 characters are not clearly shown I have not named them. 



The figures show the following forms : — 

 Clonograptus tenellus Linnarson. 

 Clonograptus tenellus var. callavei Lapworth. 

 Clonograptus sp. n. 

 Bryograptus sp. 

 Tetragraptus decipiens T. S. Hall. 



In addition, there are many fragments, suggestive but unidentifiable. 

 None of these seem to belong to genera not represented at Lancefield. Clono- 

 graptus tenellus and its numerous varieties is, outside Australasia, a typical 

 Cambrian species.* In Victoria it is, as has been shown, Lower Ordo- 

 vician.f 



The new species of Clonograptus is a fairly large one, and a perfect 

 hydrosome would probably be 6 in. or 8 in. in diameter. But there is not 

 enough of it preserved to justify description. Bryograptus is represented 



* See especially A. H. Westergard, Studier ofver Dictyograptusskiffern, &c. Lunds 

 Universitets Ansshrift. N.F., Afd. 2, bd. 5, nr. 3, 1909. 



tT. S. Hall, Proc. Roy. Soc. Victoria, n.s., vol. ii, 1899, p. 164. 



