. Bulletin of the British Museum (Natural History). THE CARBONIFEROUS PTERIDOSPERM FROND NEUROPTERIS HETEROPHYLLA (BRONGNIART) STERNBERG 159. Fig. 6 Neuropteris heterophylla. Near distal part of primary pinna, photographed with crossed-polar filters. , x %. See also Fig. 28b. pinnae are bipinnatc, one or two short, monopinnatc pinnae are intercalated on the primary rachis between them. They arc up to 2 cm long with a rhomboidal apical pinnule, and are spaced at intervals of c. 1 cm. Tertiary pinnae are attached to the secondary racheis at 8()°-90°, except near the secondary pin
. Bulletin of the British Museum (Natural History). THE CARBONIFEROUS PTERIDOSPERM FROND NEUROPTERIS HETEROPHYLLA (BRONGNIART) STERNBERG 159. Fig. 6 Neuropteris heterophylla. Near distal part of primary pinna, photographed with crossed-polar filters. , x %. See also Fig. 28b. pinnae are bipinnatc, one or two short, monopinnatc pinnae are intercalated on the primary rachis between them. They arc up to 2 cm long with a rhomboidal apical pinnule, and are spaced at intervals of c. 1 cm. Tertiary pinnae are attached to the secondary racheis at 8()°-90°, except near the secondary pinna apex where they arc more oblique (c. M"). They are spaced at intervals of 0-4 cm for the shorter pinnae, increasing to 0-8 cm in the longest preserved pinnae, and are oppositely or sub-oppositely Secondary pinnae are attached at 60°-90° (most usually c. 70°) on either side of the primary rachis. They are parallel- sided for much of their length, but are gently tapered in their distal part and terminated by a small, rhomboidal apical pinnule, c. 1 cm long. The secondary racheis arc 0-5-3 mm wide. In the distal part of the frond the secondary pinnae are monopinnatc and oppositely arranged at intervals of cm; lower in the frond they become bipinnatc and alternately arranged at intervals of up to 5 cm. Where the secondary. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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