1 92 PALEONTOLOGY 



orbital plate of the crocodile there is a similar but smaller 

 foramen. 



From these remains of the cranium of the L. pacfoygnathus 

 it is evident that the facial or maxillary part of the skull was 

 formed in the main after the crocodilian type, but with well- 

 marked batrachian modifications in the premaxillary and 

 inferior maxillary bones. The most important fact which 

 they show is, that this sauroid Batrachian had subterminal 

 nostrils, leading to a wide and shallow nasal cavity, separated 

 by a broad and almost continuous palatal flooring from the 

 cavity of the mouth ; indicating, with their horizontal posi- 

 tion, that their posterior apertures were placed behind the 

 anterior or external nostrils, whereas in the air-breathing 

 Batrachia the nasal meatus is short and vertical, and the inter- 

 nal 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 Labyrinthodon as in the crocodile ; 

 and that the skeleton of the Labyrinthodon will be found to be 

 provided with well-developed costal ribs, and not, as in most 

 of the existing Batrachians, with merely rudimentary styles. 

 Since the essential condition of this defective state of the ribs 

 of Batrachians is well known to be their fish-like mode of 

 generation and necessary distension of the abdomen, it is 

 probable that the generative economy of the Labyrinthodonts, 

 in which the more complete ribs would prevent the excessive 

 enlargement of the ovaria and oviducts, may have been similar 

 to that of saurian reptiles. 



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 load or frog, viz., 

 the convex, somewhat transversely extended articular end, the 



internal longitudinal depression, and the well-developed del- 

 toid ridge. The length of the fragmenl is two inches, and the 



