a relatively small pollen-chamber (fig. 426, A, _Pc_) like a broad and low cupola bearing a terminal beak which extended some distance into the micropylar tube. No microspores have been found in this species, but Oliver[339] records the occurrence of multicellular microspores in _Trigonocarpus pusillus_. The pedicel of the seed had a central strand of sclerous tissue penetrated by a concentric vascular bundle which gives off six strands to supply the sarcotesta (fig. 426, C, _v_) and then passes into the nucellus where it forms a tracheal sheath (fig. 426, A, _nt_) surrounding the lower part of the megaspore and at a higher level breaks up into anastomosing strands of tracheids which reach up to the plane of insertion of the pollen-chamber. [Illustration: Fig. 424. _Trigonocarpus._ 1. Section of imperfect seed showing a micropyle; _b_, sclerotesta; _c_, cast of seed-cavity; 2, 3, apical and basal view of seed-cast. (Approximately nat. size.) M. S.] [Illustration: Fig. 425. _Trigonocarpus Parkinsoni._ A. Impression showing the nucule and sarcotesta. (= _Carpolithes alata_ Lind. and Hutt.) B. Specimen with long micropyle. (A, nat. size; from the Lower Coal Measures of Kilmarnock; B, nat. size; Middle C. M. of Yorkshire. Kidston Coll., 1579 and 1062.)] [Illustration: Fig. 426. _Trigonocarpus Parkinsoni_. A, longitudinal section; _Sa_, _Sc_, _if_, sarcotesta, sclerotesta, inner flesh; _mi_, micropyle; _Pc_, pollen-chamber; _v_, vascular bundles; _m_, megaspore and prothallus; _t_, tracheal disc; _nt_, tracheids in the nucellus. B, transverse section of the upper region showing the sarcotesta, sclerotesta (black) and the micropyle. C, transverse section of _T. Parkinsoni_. D, transverse section of _Trigonocarpus shorensis_. (A, C, after Scott; B, after Wild; D, after Salisbury.)] A second species described by Scott and Maslen as _Trigonocarpus Oliveri_ has been further investigated by Salisbury who finds that it is an 8-angled seed which cannot be retained in the genus _Trigonocarpus_: its systematic position ‘must for the present remain uncertain[340].’ Dr Arber has recently described a new species of _Trigonocarpus_, _T. Moyseyi_[341], from the Nottingham Coal-field (Middle Coal Measures), similar to _T. Parkinsoni_ but much broader in proportion to its length: this species is founded on an impression without structure. The species _Trigonocarpus Dawesi_ Lind. and Hutt.[342], from the Middle Coal Measures of Lancashire, was founded on casts differing in their large dimensions from those of _T. Parkinsoni_: specimens referred to this species were described by Fiedler[343] from Saxony in 1857 and Lesquereux[344] figures similar casts from the Upper Carboniferous and Permian rocks of North America. _Trigonocarpus shorensis_ Salisbury.