Labyrinthodon /rom Warwickshire. 535 



greater than that exhibited by the same bone of a Crocodile twenty-five feet in length. 

 If both belonged to the same individual, we should have an example of a reptile 

 with hinder extremities of disproportionate magnitude as compared with those of 

 existing Saurians, but which would approximate in this respect, as in many other 

 particulars already pointed out, to some of the existing anourous Batrachians. 



That such a reptile of a size equal and in some species far superior to that of 

 the Labyrinthodon, to which the present fossils are here referred, formerly existed 

 at the period of the formation of the New Red Sandstone, is abundantly manifested 

 by the remains of those singular impressions of footsteps to which the term Chei- 

 rotherium has been applied. 



Femur. — In the same quarry which yielded the above-described iliac bone, was 

 found the hemispherical head of a femur, of a size corresponding with the articular 

 cavity or acetabulum of that bone (it is figured, below the acetabulum, in PL XLV. 

 fig. 18.). On the not improbable supposition that this is part of the skeleton of 

 the same species of Labyrinthodon as that to which the humerus belonged, the rela- 

 tive size of these bones more nearly resembles that which must have characterized 

 the so-called Cheir other ium than obtains in any recent Batrachian. 



Phalanges. — The fossil from the Warwick sandstone figured as a tooth, in the me- 

 moir of Messrs. Murchison and Strickland {loc. cit. fig. 9. PI. XXVIII.) , differs from 

 every known Saurian or Batrachian tooth in presenting a semi-elliptical transverse 

 section, being flattened on one side and convex on the other, and being unusually 

 curved. The unsymmetrical character of this fossil is so extremely rare a form in 

 the simple conical teeth of reptiles, that I applied for and obtained permission to 

 examine its intimate structure. The base of the fossil was fractured, but exhi- 

 bited no trace of pulp-cavity. A transverse section taken from its middle, and 

 viewed by transmitted light under a power of 200 linear dimensions, presented 

 numerous parallel close-set Haversian canals, with concentric lamellae surrounding 

 each, and minute and simple radiated cells in the interspaces ; there could be no 

 doubt, therefore, that it was a true bone, and I conceive it to be most probably a 

 terminal phalanx of a toe. It measures ten lines in length, is curved, and gradu- 

 ally diminishes in size from one end to the other. There is likewise in the col- 

 lection a second terminal phalanx in the form of an elongated cone, with the arti- 

 cular surface slightly concave at the base ; one side flattened, the opposite side 

 convex ; the apical extremity in both these phalanges is simply attenuated, but 

 presents no trace of nail ; they are strictly Batrachian in this respect, and from 

 their size are referable to the hind-foot of the Lab. pachygnathus. 



Thus then the fossils of the lower sandstones of Warwick and Leamington, 

 though few, bear good testimony to the affinities of the reptiles of that ancient 

 stratum. They all agree with each other and with the Mastodonsaurus Jageri 



3 z 2 



