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FOSSIL REPTILIA OF THE 



The two narrower sides are concave or flat transversely ; the broader side is gently 

 convex ; it shows, in both species (figs. 21, 23), a longitudinal linear impression, which 

 may indicate a confluent rudiment of a fifth digit. 



To the above-described, well-defined, trochlear or ginglymoid joint were adapted the 

 two obliquely disposed condyles of the distal end of the metacarpal of the fourth or 

 wing-finger. 



I have pleasure in contributing this mite of testimony to the unremitting attention to 

 the fossil evidences of Kimmeridgian Vertebrates, discovered from time to time on his 

 estates by John C. Mansel-Pleydell, Esq., F.G.S., of Longthorns, Blandford, and to the 

 wise liberality by which they -have uniformly been deposited in the National Collection, 

 where inferences and conclusions from their study can be tested by Palaeontologists. 



C. — Pterodactylus, sp. in cert . 



Two specimens of the carpal bone, provisionally referred in my Monograph of 1857 

 to a Pterosaurian ' unciforme,' 1 are figured in Plate I, figs. 24 — 27. They were both 

 obtained from the " Kimmeridge Clay," at Weymouth, Dorsetshire. 



The distal surface of the smaller specimen is given in figure 24 ; they show the larger 

 concavity (a), and the smaller one (b), adapted to the two proximal condyles of the 

 metacarpal of the wing-finger. The thenal border of the bone is the thinnest, and is 

 produced at each end into a short process ; the anconal border of the bone is thicker, 

 especially where it supports the smaller and outer articular metacarpal concavity. 



The proximal surface (ib., fig. 25) is also divided into two principal articulations, 

 but the larger one ( c ) is subdivided into a concave and a flattened facet. The smaller 

 concave surface (d) is next the outer and thickest end of the bone. 



The subject of figs. 26 and 27 is the homologous bone, and from the forelimb of the 

 same side, but it shows modifications that plainly bespeak its having come from a distinct 

 species of Pterodactyle. The outer subhemispheric concavity of the proximal surface 

 (ib., fig. 27 i?) is relatively larger, as is likewise the flat facet at the inner part of the 

 larger surface (c). The two condylar concavities (a and b) on the distal facet are more 

 equal than in the larger unciforme. 



Both bones exemplify the definite, well-marked, or finished character of the articular 

 surfaces which characterise the bones, especially those of the wing, of the volant 

 Reptile. 



I would still be understood to be guided by considerations, not beyond probability, 

 in referring this well-marked bone to the distal row of the carpal series ; for I have not 



1 Palseontographical volume for year 1857, issued in 1859, plate iv, figs. 5 and 6. 



