lieptUes and AmpJu'hians of lUinnis. 375 



a young one in which rudiments of the branchiae persist; the 

 second from an average adult; the third from a very large in- 

 dividual. (1) Body, 2 50; tail, 1.75. (2) Body, 4.19; tail, 

 3.44. (3) Body, 5.25; tail, 5.50. 



The larva3 are so remarkable as to deserve a special para- 

 graph. They differ in no essential respect from the Siredon of 

 Me.vico and our Western States, but as far as at present known 

 positively, they do not breed while in the larval condition. 

 The Siredon of the West is now known to transform into an 

 Amblystoma very similar to, and'perhaps only a variety of, our 

 species. The larva of A. tigrinum when about ready to trans- 

 form is nearly four inches in length, and, barring its legs, bears 

 an obvious resemblance to some of the fishes, notably, in the 

 shape of the head, to Pelodichthys. The body is gradually more 

 and more compressed from the head to the extremity of the 

 tail. Head deep at the base, with a uniform slope from base to 

 snout, the profile of which is nearly straight. Tongue large 

 and fleshy, mounted on thehyoid bones, and strictly comparable 

 with similar structures in fishes; the tongue of the adult Am- 

 blystoma develops later. Palatine teeth in four series, strongly 

 arched forwards, approximating and parallel with the maxil- 

 laries. Gill-opening large, making free communication with 

 the mouth. A free fold of skin continues from its anterior mar- 

 gin over the throat, uniting at an angle with one from the op- 

 posite side; and across the opening are three free arches, each 

 bearing at its dorsal extremity a branchial filament, and along 

 its inner margins a series of acute flexible processes resembling 

 the gill-rakers of fishes, which interlock when the arches are 

 closed. The anterior arch lacks the filaments on its anterior 

 side. The opening is bounded posteriorly with what is evi- 

 dently a fourth arch, though it is united behind with the 

 integument; it also bears the filaments on its anterior edge. 

 The costal folds are evident and agree in number with those of 

 adults. Limbs weak; digits flattened and pointed. The tail is 

 strongly compressed and bears a membranous expansion above 

 and below, that above extending forwards nearly to the head 

 and that below reaching the vent. 



This is our largest and most abundant salamander. It re- 

 sorts in great numbers to the ponds on prairies in early spring 

 11 



