Br. J. E. Gray on the Species of Alligators, 327 sunt, aliquando omnino absunt ; corpore subtus nigro ; antennis fusco-nigris ; pedibus fusco-nigris, tarsorum articulis anteriorum latis. Magnitudine variat ; long. corp. lin. If -ly, lat. 4-A variable species, both in pattern and size ; nevertheless the four examples before me (none absolutely identical with the three others) evidently represent a single species, which is abun-dantly distinct from all others with which I am acquainted : its elongated form, coupled with the greater breadth of the post-medial elytra (especially as contrasted with the thorax), and the distinct angle formed by the line of the margins of the elytra and thorax separate it at once from all species found in Great Britain. In our list the name will stand next to H.palustrisy Linn. Four examples of H. tinctus were detected among a mass of Turner^s captures, by my friend Dr. Power : they were captured certainly in the district of the New Forest. XXXV. — A Synopsis of the Species of Alligators. By Dr. J. E. Gray, F.E.S. &c. Having had occasion to re-examine the large collection of Alli-gators in the British Museum for the purpose of naming the more recently received specimens, I am induced to lay before the readers of the ' Annals ^ an abstract of the result of this examination. I may observe that Spix, in his work on Brazilian Lizards, gives very good figures of these animals, with the colours well marked; and Natterer, in his 'Beitrage' on South-American Alligators, gives very accurate and detailed figures of the head and the neck-shield of the difibrent species ; and he has figured some varieties or species very nearly allied to those here noticed, which I have not seen. The Alligators {Alligator idee) may be divided thus : — 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. Tro-pical America. 1. Jacare. The orbits united by a bony cross ridge. Eyelids partly fleshy, striated or rugose. 2. Caiman. The orbits not united by a cross ridge. Eyehds entirely bony, smooth. II. The ventral scutella thin, the dorsal scutella bony, not articulated together. The eyelids fleshy, smooth. The cervical scutella in pairs, sepa^ rate. Nasal bone elongate, separating the nostrils. North America. 3. Alligator. The face broad, depressed.
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