60 POMPECKJ. JURASSIC FAUNA OF CAPE FLORA. [norw. pol. exp. 



described below, can be determined, as the specimens only consist either of 

 crushed and broken fragments, or imperfect impressions and sections. 



Casts and impressions of species of various genera (Pseudomonotis, 

 Pecten, Limea, Lima, Leda, Macradon) occur, moreover, in pieces of clay sand- 

 stone, especially in somewhat coarse-grained pieces; but they are only to 

 be observed occasionally in these rocks, their remains not having accumulated 

 here in nearly such abundance as in the rock of type No. 4. 



Now and again, traces of indeterminable lamellibranchs occur in pieces 

 of argillaceous rock, and of stone marl. 



PSEUDOMONOTIS, Beyrlch. 



Pseudomonotis Jacksoni, n. sp. 

 PI. I. figs. 13—16. Letterpress fig. 9. 



1897. Avicula sp. cf. incequivalvis, E. T. Newton and J. J. H. Teall: 

 1. c. Quart. Journ. Geol. Soc. London, vol. 53, p. 502, pi. XL, fig. 4. 



In gray, hai'd, sandy marl (Aug. 2nd, 1896, 80 ft. above sea-level, ca. 

 300 m. north-west of Elmwood), are embedded numerous broken and crushed 

 shells, flattened by compression, of a remarkably large Aviculid form. Frag- 

 ments of the .same species were also found loose, weathered out of the rock 

 (also Aug. 2nd, 1896). 



The approximate outline of the shell, as far as it can be reconstructed 

 from the broken pieces, has been drawn by Newton, 1. c. 



The valves are comparatively not very oblique. The long hinge is 

 straight. The apex Hes near the anterior margin and projects only slightly, 

 if at all, over the hinge. The posterior wings are large, and their posterior 

 edge seems to me to be very slightly concave. The anterior wings are also 

 rather large, although considerably smaller than the posterior ones. The 

 valves are thick. 



The left valve is moderately convex, with the exception of the flat wings. 

 It exhibits a system of straight radial ribs. The wide spaces between the 

 15— 20(?) coarse main ribs, show 2, 3, 4, or more finer ribs, of which the 

 one in the middle is generally the most distinct. Near the inferior edge, nearly 

 all the ribs are equally coarse. The posterior wing is covered thickly with 



• Named in honour of the leader of the Jackson-Harmsworth Expedition. 



