94 :\IR. W. K. PARKER ON THE STRUCTURE AND 



Tlie roof bones {f-p.) are strong, well developed behind, where they lise over the 

 arches of the canals (figs. 1 and 3), have a small temporal wing, and are short and 

 rounded in front, wliere they leave the girdle-bone uncovered, scarcely covering the 

 great fontanelle. 



Also between the temples there is a small gap which answers to the " parietal fonta- 

 nelle" of a Liziird ; the orbital flange of each bone (fig. 3,_/!^).) is thickisli, and very 

 irreofular in outline. 



Answering to the large size of the cartilaginous ethmo-palatines the nasals (h.) are 

 huge bones, the left much the larger of the two, and sending an angular process over 

 the fron to-parietal. Their fore part is pointed and divergent, their facial or descending 

 region thick ribbed and projecting ; their top is strongly convex. 



The premaxillaries and maxillaries (pa'., mx.) are quite Ranine ; they are strong and 

 well developed. The septo-maxillaries (s.vix.) are small and inconspicuous. 



The quadrato-jugals (q.j.) are grafted on to the quadrate ; they are strong, arcuate, 

 tusk-like bones. 



Also the top of the squamosal (sq.) is like a tusk, being curved, and turning inwards 

 in front as a sharp fang ; the supratemporal part is of small extent, and the descending 

 plate long and broad. 



The parasphenoid (fig. 2, jja.s.) is perfectly normal ; it is large and swelling, has 

 a long point in frorit, its wings bent backwards, and its handle triangular. 



The vomers (fig. 2, v.) are large, many-cornered bones ; they bind crescentically 

 round the inner nostrils (i.n.), which are large, circular, and very wide apart. The 

 front process of the bone is small, not reaching nearly to the end of the subnasal 

 angle ; the terminal plo.te almost touches its fellow, is a fan-shaped tract, and ends in 

 a thick crescentic ridge, turned obliquely outwards and backwards, and armed with an 

 arched row of sharp teeth. The nasal valve-cartilages {u.P.h.I'-.) are well developed. 



This skull differs from that of a true Rana in : — 



1. The epiotic growth. 



2. The pterotic growth. 



3. Its widening roof forwards. 



4. The huge ethmo-palatine. 



5. The additional palatine bony crest. 



6. Absence of an inter-stapedial. 



7. The small extent of, and bony tract in, the basal plate. 



8. The large size of the nasals, and their want of symmetry. 



2(). CyHtignathus 1 sp.^ — Larva ; 1 incli long ; tail, | inch ; hind legs, 1 Ime. Lake 



Jannarg, Manaoo, Brazils. 



This larva of a Neotropical Frog belongs, evidently, to the same genus as the last ; 

 it is less than a third the length of the large Tadpole, whose skull has just l)een 

 described, and in development it is intermediate between the last two. 



