548 



ANTJRA 



[CH. 



is the so-called epichordal type of development. The tail vertebrae 

 are represented by a bony style, the uro style. Besides it there are 

 only nine vertebrae. The transverse processes, or " diapophyses " 

 of the ninth or sacral vertebra, to which is attached the ilium, are 

 either cylindrical as in ftana, or they are more or less wide and flat 

 as is the case in Bufo and Hyla. The diapophysis does not, like the 

 so-called parapophysis of Teleostei, represent the proximal portion 

 of the rib but is a secondary outgrowth of the neural arch-piece or 

 basidorsal and the rudimentary rib is represented by a nodule 



A B 



10 



FIG. 269. A. Dorsal view of the skull of a Common Frog (Rana temporaria) x 2. 

 B. Ventral view of the same. Both figures after Parker. 



In this and in Figs. 270 and 272 the cartilage is dotted, cartilage bones are 

 marked with dashes, membrane bones are left white. 



1. Sphenethmoid. 2. Frontoparietal. 3. Pterygoid. 4. Squamosal. 

 6. Exoccipital. 7. Parasphenoid. 8. Pro-otic. 9. Quadratojugal. 

 10. Maxilla. 11. Nasal. 12. Premaxilla. 13. Anterior nares. 

 14. Vomer. 15. Posterior nares. 16. Palatine. 18. Columella. 

 19. Quadrate. 20. Occipital condyle. n. Optic foramen. v, vn. 

 Foramen for exit of trigeminal and facial nerves. ix, x. Foramen for 



exit of glossopharyngeal and pneumogastric nerves. 



attached to the distal end of this diapophysis, which may either fuse 

 with the diapophysis as in Rana or remain distinguishable through- 

 out life as in Alytes (Fig. 267). 



The skull is constructed on the same plan as that of Molge, 

 but it is broader and flatter ; this is due to the wide arching 

 out of the upper jaws, leaving a very large opening between them 

 and the cranium. The cause of this again is to be sought in the 

 large protruding prominent eyes, so marked a feature of all Anura. 

 The floor of the cartilaginous cranium is complete in the frog, the 

 pituitary fossa having sunk to insignificant dimensions. The 

 orbitosphenoids have coalesced to form a box-like bone which ossifies 



