. Fossil plants : for students of botany and geology . Paleobotany. xxi] DIPTERIDINAE 393 Hausmannia Richteri or may be a distinct species; it shows some of the finer veins connecting the shorter forked ribs, which formed part of the reticulate ramifying system in the mesophyll. This specimen was obtained from the plant-beds of •Culgower on the Sutherlandshire coast, which have been placed by some geologists in the Kimmeridgian series. The smaller type represented in fig. 278, E, is referred by Richter to a distinct species, Hausmannia Sewardi^, founded on a few specimens from the Lower Cretac
. Fossil plants : for students of botany and geology . Paleobotany. xxi] DIPTERIDINAE 393 Hausmannia Richteri or may be a distinct species; it shows some of the finer veins connecting the shorter forked ribs, which formed part of the reticulate ramifying system in the mesophyll. This specimen was obtained from the plant-beds of •Culgower on the Sutherlandshire coast, which have been placed by some geologists in the Kimmeridgian series. The smaller type represented in fig. 278, E, is referred by Richter to a distinct species, Hausmannia Sewardi^, founded on a few specimens from the Lower Cretaceous strata of Strohberg. This species is characterised by a stouter rhizome. Fig. 289. Hausmannia sp. Upper .Jurassic, near Helmsdale, Scotland. From a specimen in the British Museum. (Nat. size.) bearing smaller leaves consisting of a short petiole (3—4 cm. long) and an obovate lamina (1—2 cm. long and broad). There are usually two opposite leaflets on each leaf-stalk, and these may be equivalent to the two halves of a single deeply dissected lamina. It is interesting to compare these different forms of Haus- mannia with the fronds of recent species of Dipteris represented in fig. 231. The more deeply dissected type, such as H. dicho- toma, closely resembles D. Lohbiana or D. quinquefurcata, while the more or less entire fossil leaves (fig. 278, E, F and fig. 289) are very like the somewhat unusual form of Dipteris conjugata shown in fig. 231, B, p. 297. 1 Kichter (06) p. 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 Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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