498 BRITISH FOSSIL REPTILES. 



of two equal-sized, closely and extensively united bones, with one or two slender stylifonn 

 ossicles attached lengthwise, having the base a little below the distal ends of the radius 

 and uhia. The latter bone shows no pits for the attachment of quill-featiiers, as in the 

 hot-blooded volant Ovipara. A carpus with one large and one small bone in a proximal 

 row, and with a second large and at least one smaller bone in a distal row, is another 

 character by which the Pterosauria manifest their closer affinity to Reptiles than to 

 Birds. The remains of the gigantic species from the Cambridge Greensands have yielded 

 the characters of the two larger carpal ossicles.^ 



Variation, as usual, begins to assert its sway as the segments of the limb recede from 

 the trunk. This is mainly shown in the relative length of the metacarpus. In Rliampho- 

 rhynchus Gemmivgi it is to the antibracliiura as 2 to 7, and to the first phalanx of the 

 wing-finger as 1 to 5, or rather less. In Bimorphodon the metacarpus is to the 

 antibrachium rather more than 2 to 6, and is little less than one half the length of the 

 first phalanx of the wing-finger. In Pterodacfi/Iiis longirostris the metacarpus is 

 two thirds the length of the first phalanx. In Pterodactylus lonyicoUum the metacarpus 

 is almost four fifths the length of the first phalanx of the wing-finger. In Pt. suevicus 

 the metacarpus is one eighth longer than the antibrachium. 



There are diversities also in the relative length of the phalanges of the wing-finger. 

 In Dimorp/iodo?i they inprease in length from the first to tlie third. In Phamphorynchm 

 Gemmiiiffi the first and second phalanges are of equal length, and the third is shorter. In 

 Pterodactylus lonyiro^tris, Pt. scolojmciccps , Pt. Kochii, they decrease in length from the 

 first to the third, and in a greater degree in Pt. suevicus. 



The most marked variety, however, if the structure has been rightly determined or 

 be not due to some accidental mutilation of the individual, is that on which Von Meyer ^ 

 has founded his genus Ornitliopterus, viz. a reduction in the number of phalanges of the 

 wing-finger from four to two, and the articulation of the proximal one to two large 

 metacarpals. The last pointed phalanx of the wing-finger in Rhamphorhyiichus is rather 

 longer than the penultimate one ; in Ornitliopterus Lavateri it is only one third the 

 length of the penultimate phalanx. 



The evidences of pelvic structure in other Pterosauria, already referred to, leaves no 

 doubt as to that in Bimorphodon, as restored at s, 62, 03, 64, in PI. 17. The 

 expansion of the ischial and pubic elements and the direction of the latter are strong 

 evidences of Reptilian aflinity, and decisive differences in the comparison with Birds. 

 Given the greatest number of vertebra; grasped by the ilia, it falls short of the least 

 number presented in the class of Birds, as by certain Natatores, which concomitantly 

 manifest a vacillating or waddling gait. Nothing in the structure, proportions, and con- 

 nections of the pelvic arch squares with the notion of bipedal progression or erect 

 sustentation of the body and wings of the Pterosaur. The share taken by the hind limbs 



1 P. 452, PI. 12, fig. 6; PI. M, figs. .5—9. 

 ^ Op. cit., p. 25, pi. vi, fig. 5. 



