548 BRITISH FOSSIL REPTILES. 



remains of a Pterosaurian, which Professor Quensted refers to my Lower-Liassic genus 

 under the name of Dimorphodon Banthensis. 



The specimen about to be described, from the Lower Lias of Lyme Regis, is 

 insufhcient to give subgeneric characters, and is provisionally registered under the wider 

 generic name. 



A. — Pterodactylus Marderi, Owen {Pterosauria, Plate 19, figs. 7, 8, 9). 



Of this species is here figured the upper or proximal half of the right humerus 

 (figs. 7 and 8). The head or articular surface (fig. 9) is a narrow, bent, or reniform 

 convexity, with the concave margin toward the thenal side of the bone (fig. 7). The 

 inner and more obtuse end of the articulation, with the tuberosity of that side, is broken 

 away ; the outer, narrower, and, in this species, pointed end is lost upon the ridge or 

 upper border of the "pectoral process" [b). The expanded part of the shaft, beyond 

 the articulation, is concave transversely' on the thenal aspect (fig. 7), convex on the 

 opposite or anconal side (fig. 8), which shows, as usual, no trace of the fossa and foramen 

 characterising that part of the humerus in Birds of flight. The antero-posterior thickness 

 of this part of the bone is less than that of the contracted cylindrical part of the shaft 

 lower down, the section of which is circular. 



This humerus, besides being smaller than that of Dimorphodo7i macronyx,^ has a more 

 straight and slender shaft, which in transverse section is more nearly cylindrical. 



B. — Dimorphodon macronyx, Owen {Pterosaiiria, Plate 19, figs. 13, 14). 



The other Pterosaurian fossil, obtained by Mr. Marder, from the same foi'mation and 

 locality, might well, by its superior size, and more ellipsoid section of the shaft , have 

 formed part of the first long-bone of the wing of the species restored in Pter., Plate 17. 



The articular surfaces of the humerus in both specimens of this Pterosaurian figured 

 (ib., Plates 15, 16, 53, 53^) were too much crushed and mutilated for profitable descrip- 

 tion. The present specimen shows instructively the distal articulation. 



The surface for the radius presents one uniform convexity, a, oblong in shape, and 

 obliquely disposed, extending from the lower part of the radial ridge (c), upward, forward, 

 and ulnad; it is almost wholly developed from the thenal aspect (fig. 13), only the lower 

 border of the convexity being visible from the anconal side (at a, fig. 14). It is longer 

 and more prominent than the ulnar convexity or condyle. This (ib., j) is subhemisphei-ical ; 



1 ' Monograph of Liassic Pterosauria,' Pal. vol. for year 1869, pi. xviii, figs. .53, 53 a. 



