Fossil Plants from Tanganyika. 391 



Tanganyika territory : from near Kissakki,^ about 180 miles south, 

 of the Tanga Hinterland ; from the Uchunga Mountains,^ rather 

 more than 100 miles south-west of Kissakki ; from Ituli,^ 500 miles 

 south of Tanga, and from the southern extremity of Lake Nyasa,* 

 slightly over 400 miles south-west of Ituli. 



The description by Zeiller in 1883 of certain European species of 

 Upper Carboniferous plants from the Tete basin (Zambesi) seemed to 

 prove the existence during the period of the Coal Measures of a 

 northern flora in close association with the southern or Glossopteris 

 flora, and it was assumed that Glossojiteris and its associates were 

 absent from the Zambesi basin. A few years ago Dr. Potonie showed 

 that the plants described by Zeiller could not have been collected 

 in situ, but were of European origin ; he also demonstrated the 

 occurrence of Glossopteris, and so proved the extension of the 

 Glossopteris flora into the region of the Tete basin. 



The genus Voltzia was recorded by Feistmantel ^ from Lower 

 Gondwana rocks in India in 1881 ; the vegetative shoots assigned by 

 him to the European Bunter species Voltzia hetero'phylla Brongn. 

 mav or may not be correctly determined. A recent examination of 

 H lobed scale of the Voltzia type, figured by Feistmantel, led me to 

 regard it as affording evidence in favour of Feistmanters 

 determination.^ As already stated, authors have not been consistent 

 in the use of the generic names Ullmannia and Voltzia, and, indeed, 

 no clear distinction can be drawn in the absence of reproductive 

 organs. Specimens of vegetative shoots of the [Ulmannia or Voltzia 

 habit occur in the Permian of Europe as well as in the three series 

 of the Triassic system.' Shoots of this general type are on the whole 

 more characteristic of northern than of southern floras. 



Taking into account the whole of the palaeo botanical evidence, 

 my opinion is that while some of the specimens agree more closely 

 with European Zechstein forms than with any later species, the 

 balance of evidence points to a higher horizon, whether Triassic or 

 Rhsetic cannot be definitely determined. If it is assumed that the 

 absence of Glossopteris means its non-existence in the Tanga flora, 

 this would furnish an argument in favour of a geological position at 

 least as high as Uppermost Triassic or Rhaetic. Glossopteris lingered 

 on into the Upper Triassic period in Natal and Indo-China,"^ and while 



^ H. Potonie, lac. cit. 



2 W. V. Brehmer, Bot. Jahrb. {A. Engler), Bd. li, Heft 3 and 4, 1914, p. 399. 



3 E. A. N. Arber, Quart. Journ. Geol. Soc, vol. Ixvi, 1910, p. 237. 



* H. Potonie, Palaeobotanische Zeitsch., Bd. i, Heft i, 1912, p. 36. See also 

 Potonie, " Die fossile Flora des Tete-Beckens am Sambesi " : reprint from the 

 Branca Festschrift, 1914 (Berlin). 



° O. Feistmantel, Foss. Flor. Gondwana System, vol. iii, pt. iii, 1881. 



^ A. C. Seward and B. Sahni, " Indian Gondwana Plants: a Eevision " : 

 Mem. Geol. Surv. India, vol. vii, 1920, p. 1. 



'' E. Schiitze, " Beitrage zur Kenntniss der Triassischen Koniferen-Gattungen 

 Pagiophyllum, Voltzia und Widdringtonites " : Jahresheft Ver. Vaterl. Natur- 

 kunde in W urttemberg, 1901, p. 256. 



* A. L. du Toit, South African Journ. Sci., vol. xviii, 1921, p. 120. 



