REPTILIA. 253 



into numerous folds, four toes on the anterior, and five on the posterior 

 feet. The tail is much compressed, and the soles of the feet margined 

 with a fold of skin enabling the animal to move with facility in the water. 

 It is known generally as the " alligator," although, of course, improperly ; 

 and spends most of its time in the water, very rarely coming upon land, 

 except possibly at night. These animals are exceedingly voracious, feeding 

 on insects, fish, and, in some known instances, small mammalia. They 

 bite at a baited hook, in the spring and autumn, with as much greediness 

 as fishes, and are frequently caught in this way, to the great disappointment 

 of the western angler, who, in most cases, is so much afraid of his prize as 

 to cut the line rather than risk the danger of contact with so repulsive an 

 object. No danger exists, however, as the animal, with his short teeth, is 

 unable to produce any injury, even if willing to do so. It sometimes 

 attains a large size, as upwards of two feet, although the average is, 

 perhaps, twelve or fifteen inches. Little is known of its larval history, 

 except that it loses its external gills when only a few inches long. The 

 known species are M. alleghaniensis, from the waters of the Mississippi, 

 and M. fusca, from those of South Carolina and Georgia. The next, and 

 last, living genus of this family is Megalohatrackus, the most gigantic of all 

 living Balrachla iirodtla. It resembles Menopoma closely in appearance, 

 the principal difference being found in the entire obliteration of the lateral 

 cervical foramen. The single species, M. sieholdtii, inhabits certain ele- 

 vated lakes ni Japan, where it grows to a great size. One specimen, now 

 or recently living in the Museum at Leyden, exceeds three feet in length, 

 weighing upwards of eighteen pounds. 



The passage from the Menopoma to Megalohatrachus is to be found in 

 a gigantic fossil genus, Andrias, from the fossiliferous marls of CEningen, 

 Scheuchzer, who published the first description of the single species, A. 

 scheuchzeri, called it Homo diluvii testis ; being impressed with the idea 

 that the skeleton obtained was human, and, as he thought, entombed by the 

 Noachian deluge. In size it is about equal to that of the Japanese giant, 

 from which it differs in having the peculiar structure of the petrous and 

 pterygoid bones, as well as the great breadth of the head observed in 

 Menopoma. The anterior toes are longer in proportion than in the allied 

 genera. 



The sub-order of Ati'etodera, to which we are led by the genus Megalo- 

 hatrachus. are without branchial apertures or gills when in the adult state. 

 Although there is a great variety of form in this sub-order, yet it is difficult 

 to constitute more than one family, that of the BalamandrincR. Of the 

 three principal regions of the salamanders, Europe, Japan, and North 

 America, each is characterized by some peculiarity of structure. Thus 

 while most of the European forms have parotid glands, like those of the 

 toad, and one at least of the Japanese is provided with temporary claws, 

 the American alone have teeth on the sphenoid bone : neither is there any 

 vestige of the parotid gland, above referred to, in the latter. 



The salamanders were formerly divided into two great genera, 8ala- 

 mandra and Triton ; the former with rounded tail and terrestrial habits, 



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