( \ ! \1 OOUE OF SHIELD REPTILE8. 



ad \ ;irit-ty. and also in doubting it' 

 the ■ are both from America. 



men in the l>ri t i^H Museum proves most di- 



thal there are two very distinct Alligators with 



bonj oyclida fonnd in Tropical America ; which agrees well 



th the oharaotor that M. Cnvier and MM. Dumeril and 



Bibi varioties of thai species; and these 



i . 9TV08, as distinct from one another 



as ( trnu from 0. vulgaris. The heads of both 



are figured bj Dr. John Natterer in his 



" 1 b Lmerioan Alligators" in the Vienna 'Transac- 



ti.'i. tuthor also figured a third species, which he 



-. which, it' it is separable from A, trigo- 



ttus, must he distinguishable from it bj very Blight cha- 



racb 



The Black Crocodile (ffaler\ ,'o-osa) of West 



muoh resemblance to this animal that Cuvier 

 ddered Adanson's West-African specimen a variety of 

 this sp 



Burnetii ami Bibron evidently considered the African 



lonerican animals the same species ; and we a short 



time ago received from M. Braconier, of the Jardin des 



Plantes, a skeleton of the African species Hahrosia nigra 



under the name of Alligator palpebrosus, var. 



A. //, :■> shelving on the sides. Nuchal scutella in a single 

 • al scut,lla five pairs ; dorsal scu- 

 Ulla highly heeled, irregular, in six series; the lumbar 

 Scutella in two longitudinal series ; the gular and two 

 outer lit, ral s< ries of ventral scutella heeled. The fiat 

 upper dish at the base of the tail broad and strongly 



Palcosuchns, Gray, Ann. $ Mag. Nat. Hist. 1862, x. p. 330. 



1. Caiman trigonatus. (Rough-backed Alligator.) B.M. 



Crocodilus trigonatus, Schn. Amph. p. 151, vi. 

 Tie* . Amph. p. 66, t. 67. 



Crocodilus palpebrosus, var. 2, Cuvier, Oss. Foss. v. n 40 

 t. 2. f. 1. l 



- • itus, Gray,Oat. Tort. Sfc. B. M. p. 66 ; Ann. 

 X Mag. Nat. Hist. x.'p. 330, 1862 ; Trans. Zool. Soc. vi. 



p. i»;;. 1869. 



palpebrosus, Br'uhl. Skelet. Kroc. t. 19. f. 3. 

 mpsa trigonata, Natterer, Beitr. t. 26 (good). 



Sab. Tropical America. 



The largest specimen in the British Museum is rather 

 ve 4 6 . t long. The young specimens have the lateral 

 ventral shields keeled. 



It. Head flat, and erect on the tides. Nuchal scutella many, 



in two cross s, ries : R rricul scut, 1/n three pairs ; dorsal 

 scut, 11a slightly heeled; tin lumbar scutella in four 

 longitudinal series; (he gular, (he ventral, and the 

 lateral abdominal scut, lb, heeled. The flat upper dish 

 at th, I, ns, of tb, tail etongaU . 



Aromosuchus, Gray, Ann. tj- Mag. Nat. Hist. x. p. 330. 



2. Caiman palpebrosus. (Banded Alligator.) B.M. 

 Brown ; tail black-banded. 



Crocodilus palpebrosus, var., Cuvier, Oss. Foss. v. t. 1. f. 6- 



1 7, and t. 2. f. 8. 

 Cnampsa palpebrosa, Natterer, Beitr. t. 27 (good). 

 Caiman (Jacaretinga) moscbifer, Spiat, Bras. t. 1 (skull). 

 Caiman palpelirosus, Gray, Cat. Tort. t$r. B. M. p. 67; Ann. 



4" Mag. Nat. Hist. x. p. 330, 1862 ; Trans. Zool. Soc. 



L869, vi. p. 167. 

 Crocodilus palpebrosus, Tiedm. Nat. Amph. t. 6. 



Burm. Gavial. t. 1. f. 1, 2, & t. 3. f. 3 (head). 

 Alligator palpebrosus, Merrem, Syst. p. 35. 

 Gray, Syn. Sept. p. 63. 



Hub. Tropical America. 



Natterer figures the head of a species under the name of 

 C. gibbiceps ; but I do not see how it differs from the above, 

 except that the head is a little higher — perhaps a sexual 

 distinction. Dr. Strauch regards C. gibbicepis as the same 

 as C. palpebrosus. 



Section II. The ventral scutella thin, the dorsal scutella 

 bony, not articulated together. The eyelids fleshy, 

 smooth. The cervical scutella in pairs, separate. Nasal 

 bone elongate, separating the nostrils. North America. 



3. ALLIGATOR. 



Head depressed, broad, without any ridges in front of 

 the orbit. Snout very broad, flattened and rounded at 

 the end, the ninth maxillary tooth the largest. The eye- 

 lids smooth, fleshy. The dorsal scutella not articulated 

 together, in six longitudinal series; the ventral scutella 

 thin; the gular and abdominal shields smooth; nuchal 

 scutella one pair, small; cervical scutella three pairs, 

 hinder smallest. Nostril separated by a bony septum. 

 The feet webbed. Dorsal plates in six longitudinal series, 

 the two vertebral closer together. The sides with a short 

 series close to the others, sometimes reduced to only one 

 or two shields. 



Alligator, Gray, Cat. Tort. B. M. p. 66 ; Ann. $ Mag. Nat. 

 Hist. x. p. 330, 1862 ; Trans. Zool. Soc. 1869, vi. p. 168. 

 Huxley, Proc. Linn. Soc. iv. p. 3. 

 Champsa, Wagler, Syst. Amph. p. 14U. 



