94 Arber. — A Revision of the Seed Impressions of the 
think that more than three wings occur, though this conclusion is at present 
provisional. 
The only seed with which I can compare the British Museum specimen 1 
is Grand’ Eury’s 2 Carpolithes oblongus , from the Stephanian of the Loire. 
Here, however, the seed is only half the size of the British example. I 
believe that both these seeds belong to the same genus, for it will be remem- 
bered that Grand’ Eury also concluded that his seed had three wings. 
I think this type is certainly worthy of removal from the nondescript genus 
Carpolithus , and to be placed in a genus of its own, for which I propose the 
name Pterospermum (‘ winged seed ’). As the British example appears to 
be of so very different dimensions to the French, I propose to distinguish 
the former as Pterospermum anglicum , sp. nova. 
Systematic List of British Coal Measure Seed Impressions. 
Genus Trigonocarpus, Brongniart, 1828. 
Pleomorphic impressions or casts of seeds, of medium or large size, 
elongately oval, usually longer than broad, unsymmetrically winged, the 
apex being produced into a micropyle. Testa differentiated into a soft 
outer sarcotesta and a hard inner sclerotesta. Inner surface of sclerotesta, 
with three well-marked grooves, appearing as three longitudinal ridges on 
the casts of this surface, more or less equidistant. 
(1) Trigonocarpus Parkinsoni , Brongn. 
T. Parkinsoni , forma a. Impressions of the external surface of the 
seed. Type Carpolithes alata , Lindley and Hutton, £ Fossil Flora,’ Vol. ii, 
PL LXXXVII, Figs. 1-3, 1833. Recorded from the Transition, Middle, 
and Lower Coal Measures of many of the Midland,, Pennine, North of 
England, and Scottish coalfields. 
Seed elongate, oval, 3*5~5*5 cm - l°ng> and 1*5-2 cm. across at greatest 
width. Micropyle about 1 *5-2*5 cm. long, sarcotesta smooth, sclerotesta 
oval, about 1*8 cm. long and i*2 cm. broad at its greatest width. 
T . Parkinsoni, forma ft (PL VI, Fig. 2). Impressions of the sclerotesta 
and micropyle. Type Rhabdocarpus Bochschianus , Berger, ‘ De Fruct. et 
Semin. Form. Lith.,’ p. 21, PL I, Figs. 13, 14, 1848. Records as above. 
Sclerotesta oval, smooth, not ridged, i*8 cm. long and 1*2 cm. at greatest 
width. Micropyle 1*5-2 cm. long. 
T. Parkinsoni, forma y (PL VI, Figs. 3-5). Casts of the inner surface 
of the sclerotesta. Type Trigonocarpum Noggerathi, Lindley and Hutton, 
‘Foss. Flora,’ Vol. ii, PL CXLII, Figs. C 1-3, 1833-35. Records as above. 
1 This specimen has for many years past been labelled with a MS. name of Dr. Kidston’s. 
2 Grand’ Eury ( 77 ), p. 187, PI. XV, Fig. 9. 
