44 CROCODILIA. 



keeled or keelless, and arranged in two or more rows; ventrals 

 (when present) in eight or more rows. 

 This group includes the Mesosuchia of Huxley \ 



A. PROCCELIAN SERIES. 



Vertebrae, except atlas, axis, sacral, and first caudal, proccelous 2 . 

 Pterygoids developing palatal plates to prolong narial passage ; 

 lateral eustachian passages bony. Dorsal scutes keeled, in more 

 than two rows ; ventral buckler (when present) single, with more 

 than eight longitudinal rows of imbricating scutes, each scute con- 

 sisting of an anterior and posterior element united by suture. 

 Acetabular margin of pubis deeply notched. 



Family CROCODILIDiE. 



The orbit communicating with the infratemporal fossa, and 

 generally larger than or equal to the supratemporal fossa ; on the 

 palate the posterior border of the premaxillae either slightly concave 

 posteriorly, straight, or projecting into the maxillae. Usually no 

 preorbital vacuity. 



BREVIROSTRINE SECTION. 



The cranium short or moderately elongated, with its alveolar 

 border festooned ; the nasals reaching the premaxillae, and frequently 

 the nares ; the orbits larger than the supratemporal fossae ; the 

 premaxillary fissure either heart-shaped or slit-like ; the mandibular 

 symphysis more or less short, and without a splenial element. The 

 teeth more or less differentiated ; usually the 3rd and 9th upper, and 

 the 4th and frequently the 1st and 11th lower, enlarged. Dorsal 

 scutes strongly keeled and usually comparatively narrow. Ventral 

 armour present or absent. 



Genus ALLIGATOR, Cuvier 3 . 



Including Caiman and Jacare. 



Cranium short and broad, with the palatal aspect of the pre- 

 maxillae short, and their posterior border straight or concave poste- 



1 In order to avoid confusion the writer, who at one time proposed the name 

 Crocodilia Vera for this suborder, subsequently came to the conclusion that it 

 was better to retain the earlier name in a wider sense. 



2 It is of course possible that a form may be found haying the pterygoids 

 with palatal plates, but still retaining amphiccelous vertebras. 



3 Ann. d. Museum, vol. x. p. 25 (1807). — As a subgenus. 



