SKULL OF RANA TIGRINA. 



The S])heneihmoid (text-figs. 1, 2, 3, 7, 8, and 9, se.) is more 

 strongly developed than in the European species, and extends 

 posteriorly almost to the region of the optic foramen. Anteriorly 

 it extends on either side so as to form a part of the anterior 

 boundary of the orbit {vide text-fig. 8) ; this feature is much 

 better marked in the advilt specimens. In the average adult 

 specimen its front portion forms more than half the extent of the 

 nasal roof, floor, and the middle wall. In a dorsal view a lozenge 

 or diamond-shaped area of this bone {vide text-fig. 1) is left 

 between the nasals anteriorly and the anterior median notch of 

 the fronto-parietals behind. 



Text-fioure 8. Text-fio-vire 9. 



i?. tigrina. 



Text-fig. 8. — Splienethinoid, dorsal aspect after removal of investing bones. 

 se., splienethmoid ; p., palatine ; p.c, palatal cartilage. 



Text-fig. 9. — Splienethmoid, anterior aspect. 



I., apartm-e for olfactorj- nerve ; vp-, septum. 



The cartilaginous skeleton of the nose does not call for any 

 special remarks, except that in addition to the rhinal process 

 (text-fig. 7,j»j.rA.) there is a median prenasal rostrum {p.r.) in 

 continuation of the septum nasi {s.n.). A definite septo-maxillary 

 (sm.) is present on either side, extending horizontally from the 

 anterior wall into the nasal cavity, though Parker (4) regarded 

 them as mere ossifications in the nasal cartilage. 



The Bones of the Face. 



The Nasals (text-figs. 1, 3, & 5, rt,.) are large broad-based 

 triangular bones, meeting each other in the middle line and 

 diverging posteriorly to enclose the diamond-shaped area of the 

 splienethmoid referred to above, and to- meet the anterior ends of 

 the fronto-parietals. Anteriorly also they extend as far forwards 

 as nearly to reach the nasal processes of the premaxillfe. The 

 apex or external angle of the triangular bone is drawn out and 

 extends outwards to meet the ascending process of the maxilla. 



The Vomers (text-figs. 2 & 6, v.) meet each other in the middle 

 line posterioi-ly, but diverge anteriorly leaving a portion of the 



