LABYKINTHODONTIA. 213 



The remains of the cranium of the L. pachygnathas, shew 

 that it had subterminal nostrils, leading to a wide and shallow 

 nasal cavity, separated by a broad palatal flooring from the 

 cavity of the mouth, the passage being horizontal, and the 

 internal apertures placed behind the external nostrils, whereas 

 in the air-breathing Batrachia the nasal meatus is short and 

 vertical, and the internal apertures pierce the anterior part of 

 the palate, suitable to their mode of breathing by deglutition. 

 It may be inferred, therefore, that the apparatus for breathing 

 by inspiration must have been present in the Labyrintlwdon, 

 and that the skeleton will be found to be provided with well- 

 developed costal ribs. 



Of the few bones of the extremities which have come under 

 the writer's inspection, one presents all the characteristics of 

 the corresponding part of the humerus of a toad or frog, viz., 

 the convex, somewhat transversely extended articular end, the 

 internal longitudinal depression, and the well-developed del- 

 toid ridge. In its structure, as well as in its general form, the 

 present bone agrees with the batrachian, and differs from the 

 crocodilian type. The two toe-bones, or terminal phalanges, 

 resemble those of Batrachians in presenting no trace of a nail, 

 and from their size they may be referred to the hind feet of 

 the L. pacliygnathus. 



In the right ilium, about six inches in length, and in the 

 acetabulum, there is a combination of crocodilian and batra- 

 chian characters. The acetabular cavity is bounded on its 

 upper part by a produced and sharp ridge, as in the frog, and 

 not emarginate at its anterior part, as in the crocodile. 



As the fragment of the ilium was discovered in the same 

 block as the two fragments of the cranium and the portion of 

 the lower jaws, it is probable that they may have belonged to 

 the same animal ; and if so, as the portions of the head corres- 

 pond in size with those of the head of a crocodile six or seven 

 feet in length, but the acetabular cavity with that of a crocodile 



