or EECENT CEOCODILIANS. 161 



large square keeled shields. Back scale keeled, the three last cross hands of four scales 

 Sides with some strong keeled scales. Back green, black-dotted. 



3. A. punctulatus, p. 91, Spix, Bras. t. 2. Head elongate, nose flattened, with a 

 rounded point in front, without any preocular ridges, upper eyelid rugose. Nape with 

 two rows of shields. Back flat, scarcely keeled. Sides with some larger scales. Yellow, 

 black-dotted. 



John Natterer, in his "Beitrag zu den Siid-Amerikanischen AUigatoren," edited by 

 Fitzinger, describes eight species of the genus Champsa : five have partly bony eyelids, 

 and three have them entu'ely bony. The five former belong to the genus under con- 

 sideration. 



The preorbital ridge distinct, beak broad with three lateral foveolse, eyelid striated, 

 beak broad and blunt. C. nigra, t. 21. 



The nuchal scutella many, in three series. C.fissipes, t. 22. 



The nuchal scutella many, in two series. G. sclerops, t. 23. 



The preorbital ridge evanescent, beak without lateral foveolse, eyelids rugose. Tlie 

 frontal ridge flexuous, bent in front. C. vallifrons, t. 24. 



The frontal ridge arched, bent back. C. punctulata, t. 25. 



M. Natterer gives the following proportional measurements of the heads : — 



Length of Width of Width of Beak 

 Length of Width of Crown Crown above the 



Head. Head. before. before. eighth tooth, 



in. 1. in. 1. in. 1. in. 1. in. 1. 



Champsa nigra 16 8 3 6 4 5 1 



fissipes 10 3 6 5 2 7 3 .5 4 



. sclerops 6 6 5 8 2 8 3 3 3 3 



vaUifrons 7 10 4 6 2 2 9 2 3 



punetiilata 10 5 5 4 2 5 3 2 2 5 



The figures of the heads of the last two species differ from that of C. sclerops chiefly in 

 the nose being narrower (C. punctulata being the narrowest and very slender), narrower 

 than in any specimens that have come under my observation ; the lower jaws in the 

 figm-e also differ in shape, that of C. wdUfrons being the most slender. Dr. Strauch, 

 who had M. Natterer's specimens to examine, regards the two latter as the same species, 

 but distinct from sclerops. 



Synopsis of Genera. 

 I. The ventral scutella like the dorsal ones, bony and articulated together, forming a 

 shield. The eyelids with an internal bony plate. The cervical scutella in pairs, 

 forming an elongated shield. Nasal bone short. Tropical America. 



1. Jacaee. The orbits united by a bony cross ridge. Eyelids partly striated or 



rugose. 



2. Caiman. The orbits not united by a cross ridge. Eyelids bony, entirely smooth. 



