VI.j 



THE COMMON FROG. 



8i 



In a certain frog before noticed, called Pelobates, as 

 also in CalyptocepJialiis, a similar view of the skull 

 exhibits no such great vacuity. The reason of such 

 absence is that the temporal fossa in these animals 

 is roofed over and enclosed by the meeting together 

 of bony lamellae developed from the bones surround- 

 ing it, which thus bound the orbit posteriorly, and 

 give to the cranium an altogether false appearance of 

 great capacity. 



Fig. 45. — Lateral view of skull of Turtle {Ckelonia), showing bony lamellae behind 

 the orbit, a, naso-praefontal ; b, maxillary ; c, palatine ; d, basi-sphenoid ; e, 

 praemaxillary ; /, frontal ; g, post-orbital ; h, parietal : t, jugal : k, quadrato- 

 jugal : /, quadratum ; vi, squamosal; /, super-occipital; i, dentary ; 3, an- 

 gular ; 4, surangular ; 5, articular ; 6. coronoid. 



This very singular structure is found to exist also 

 in the marine turtles, amongst the Chelonians, and 

 here we have another striking resemblance between 

 the Chelonia and the Anoura, apparently reinforcing 

 the argument for the existence of real affinity derived 

 from the presence of such bony dorsal shields in both 

 those two orders. The importance of this character 

 might seem the more unquestionable, since no other 

 reptiles and no birds or beasts whatever were known 

 •to exhibit a similar structure. 



Quite recently, however. Prof. Alphonse Milne- 

 Edwards has described a beast from Africa {Lophio- 

 mys) belonging to the Rodent (rat, rabbit, and squirrel) 



G 



