Bd. III: 14) 
THE MESOZOIC FLORA. 
7 
with that of the intercommissural segments. The latter taper quickly, so that their 
edges meet a short distance above the base of the free teeth. The marginal parts 
of the latter are formed by thinner tissue which is continuous downwards with that 
of the commissural furrows. In the upper portion of the free teeth only the vein- 
like median line represents the direct continuation of the intercommissural segments) 
as is seen in text-fig. i. 
The variation in the breadth of the stem and in the number of segments which 
is seen in the specimens figured in pi. i, might possibly be taken to indicate a 
difference of species. It is probable, however, that all the specimens belong to one 
species, since the extreme forms are connected by intermediate 
stages. The illustration of the broad specimen in fig. ii, pi. i, 
is somewhat incorrect. The portion to the right of the dia- 
phragm is at a different level in the matrix and belongs pro- 
bably to another superimposed stem. This might be inferred 
already from a consideration of the breadth of the stem as 
compared with that of the diaphragm seen at the node. Even 
as it is, the stem is a little broader than the disc but not 
more than it should be on account of its flattened condition. 
The diaphragms are of the shape usual in the genus, with 
radiating scars corresponding more or less in number to the 
segments of the leaf-sheaths. In the specimen shown in fig. 1 1 the radial marks reach 
nearly to the centre of the disc, in the one in fig. 14 they are much shorter, but 
otherwise there is no difference. 
Of all the better known Jurassic forms of Equisctitcs^ the present species appears 
to come nearest to E. Duvalii Saporta (1873, p. 248; pi. 30, figs, i — 4). E. Duvalii 
has similar short internodes as the Antarctic specimens and about the same number 
of segments; but, according to Saporta’s illustrations, the teeth had not the thin 
membraneous edge characteristic of the latter species. The same character distin- 
guishes our plant from E. colitinnaris Brgn., which comes near to E. Duvalii but 
generally is much stouter and has much longer internodes. The diaphragms figured 
in pi. I resemble very much those of E. lateralis Phillips, which is identified by 
Seward with E. cohnnnaris. 
There is also a great resemblance, as regards both stems and diaphragms, to 
E. Rajinahalcnsis ScHiMP. (Feistmantel, 1877«, p. ii; Oldham &: MORRIS, 1863; 
jol. 2, figs. 2 — 5; pi. 35, figs. 3—4) from the Upper Gondwanas of India, and it might 
with some probability be suggested that both forms are identical; but there is too little 
material of the Indian species available for comparison. Some of the specimens 
figured by Ward (1905, pi. 72, figs, i — ii) as Equiscturn Phillipsii (Dunk.) have 
diaphragms very much like those of the present species, and also the teeth are some- 
Fig. I. 
Equisetites approximatus 
Nath. n. sp. 
Portion of leaf-sheath, ^/i. 
