Notes on Trigonocarpus and Polylophospermum. 97 
Polylophospermum. The specimens were derived from some uncut 
blocks from the well-known locality Grand ’Croix which had been 
incorporated in the Williamson Collection many years ago. 
Through the courtesy of Mr. Smith Woodward, F.R.S., Keeper of 
the Geological Department of the Natural History Museum, faci¬ 
lities were obtained for preparing microscopical preparations of the 
seeds. So far as these specimens are concerned, the chief interest 
lies in the structure of the nucellar wall, and in the possible relations 
of the nucellus to the integument, and in certain indications which 
point to the existence of an outer fleshy coat to the testa. The 
seeds though not new have never been described with that fulness 
of detail which is desirable in view of the attention that is now 
being directed to the phylogeny of the Gymnospermous series. 
In the present note only a few points come up for consideration 
owing to the incomplete character of the preservation. 
Trigonocarpus pusillus, Brongniart, 1 the first of these specimens 
to be described here, is one of the smallest of palaeozoic seeds. It 
was originally described and figured by Brongniart, but without any 
elaboration of detail. 2 It is an elliptical seed with beaked micro- 
pylar extremity; the testa shews three longitudinal sutures, but is 
without wings. The hard shell is described as very compact and as 
shewing a palisade layer (“cellules rayonnantes”) at the surface. 
The dimensions given are 7—8 /;//;/. x 4—5 mm. The nucellus 
occupies the interior of the seed and possesses a somewhat tapering 
or conical pollen-chamber in which pluricellular pollen-grains occur. 
A single vascular strand enters at the chalaza and expands into a 
vascular (tracheal) investment of the nucellus, lying in the sub¬ 
stance of the latter between the epidermis and the macrospore 
wall. In transverse section the nucellus is angled in correspondence 
with the testa, and Renault contributes the additional fact that the 
angles of the nucellus are attached to the testa along these lines, 
so that the seed in this respect resembles a Pachytesta in miniature. 8 
Our own specimen is 6| mm. in height x 4£ mm. maximum 
1 The Trigouocarpoiis first described by Hooker and Binney 
(Phil. Trans. 1855, p 149) from petrifactions, were regarded 
by Brongniart (Les graiues fossiles, p. 26) as probably 
belonging to his genus Tripterospcrmum , which differs from 
Trigonocarpus\n possessing distinct wings along the sutures. 
The Trigonocarpon olivaeformc of Williamson’s 8th Memoir 
(on the Organisation, &c., Phil. Trans. 1877, p. 213), is 
doubtless an identical or very nearly related seed. In an}' 
case the structural feature used by Brongniart to separate 
Trigonocarpus and Tripterospcrmum seems unimportant. 
2 Les graiues fossiles silicifiees, pp. 24,25 and PI. B, figs. 1, 2 and 3. 
Plore fossile d’Autun et d’ Epinac, pt, 2, p. 398. 
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