88 Arber . — -z/ Revision of the Seed Impressions of the 
unsymmetrical nucule, enclosed in a large unsymmetrical wing or sarcotesta, 
the seed being apparently symmetrical only in one plane. The fact that 
the sarcotesta is ornamented with close, parallel, longitudinal striae is 
probably of no systematic importance, for the same feature occurs in the case 
of other platyspermic and also among radiospermic seeds. My conclusion 
is that this Stephanian and Permian type of seed has been hitherto unknown 
from the British Coal Measures, and that all the British species so far 
referred to it are symmetrical in two planes, and are not obviously winged. 
I therefore propose to transfer them to a new genus, Platyspermum . 
P. sulcatum, Sternb. (Pl.VI, Fig. n), and P. elongatum , Kidst. (PI. VI, Fig. 12), 
belong here, and so does the true P. multistriatum of Sternberg. The 
specimen from the Radstock coalfield, figured by Dr. Kidston 1 under this 
name (PI. VI, Fig. 9), I believe to be a new species, and not Sternberg’s seed. 
I have included it here as P. Kidstoni, sp. nova, and have also figured what 
I take to be the true P. midtistriatum of Sternberg (PI. VI, P"ig. 10). 
P. Kidstoni appears to me to lie nearer to P. sulcatum, , Sternb., than to 
P. multistriatum , Sternb., in that the ridges approximate at the base and 
apex. I, however, only know Dr. Kidston’s specimen from the published 
drawing. Another new species, P. rugosum , with coarse ribbing, is also 
described here (Plate VI, Fig. 13). 
While the above species, here referred to the new genus Platyspermum , 
are in my view morphologically distinct from Rhabdocarpus tunicatus , Berg., 
and R. subtunicatus , Zeill., there is, however, one seed known to me which 
does appear to be a true member of the latter genus. Two examples of 
this are figured on Plate VII, Fig. 21. It is apparently a new species which 
I propose to call Rhabdocarpus Lillie anus, sp. nova. 
The genus Platyspermum is not intended to include all platyspermic 
seeds of Coal Measure age, but only those which are not winged and in 
which the testa possesses many close, parallel ribs or striations. There are 
several other types, among which are : 
Cornucarpus , gen. nova. 
This new term is proposed for a well-known platyspermic seed, sym- 
metrical in two planes, which is very distinct from all other seeds. It was 
first described by Lindley and Hutton 2 in 1833 as Cardiocarpon acutum 
(PI. VI, Fig. 14, and Text-fig. 2, p. 97). There is considerable evidence for 
believing it to be the seed of Eremopteris artemisiaefolia , Sternb., but it has 
not yet been possible to demonstrate actual continuity between this seed 
and the fertile fronds of that species. Some years ago Dr. Kidston showed 
me prepared specimens of this seed rendered transparent, so that the pollen 
1 Kidston (’88), p. 404, PI. XXIII, Fig. 4. 
2 Lindley and Hutton (’31), vol. i, p. 209, PI. LXXVI. 
