278 BULLETIN 34, UNITED STATES NATIONAL MUSEUM. 



extremicy of the supraorbital. Tympanic disk distinct; vertically oval 

 in form; its long diameter two-thirds that of the orbit. Tarotoid gland 

 elongate, with oval extremities; not angulate nor descending on the 

 sides of the body. Dorsal derm studded with rather small round warts. 

 Surfaces of limbs and lower parts everywhere strongly granular. First 

 finger a little longer than second. Toes webbed, the membrane emargl- 

 nate to opposite the middle of the fourth (first) phalange, leaving the 

 distal phalanges with a dermal margin only. Metatarsal tubercles two; 

 the internal large, narrowed, and with a short free cutting edge; the 

 external small and without cutting edge. The length of the head to the 

 posterior extremity of the longitudinal crests enters the totnl length 

 from three and a half to five times, differing in the subspecies. 



The color of the species is brown above, with darker brown subround 

 dorsal spots with pale edges and of moderate size, arranged in from 

 two to four rows on each side of the middle line. The latter is generally 

 marked by a more or less distinct pale streak. There is frequently, but 

 not always, a dark brown lateral shade, which commences below the 

 posterior end of the parotoid gland, and has a pale superior, but no dis- 

 tinct inferior border. It may be broken into spots. The limbs are brown, 

 cross-banded, and the inferior surfaces are pale yellow, Avhich is very 

 rarely dark spotted, and then only on the thorax. 



The size varies from three to five inches in length of head and body. 



In its distribution this species is one of the most widely diffused of 

 the cold-blooded vertebrates of Forth America, and as such presents 

 several strongly marked geographical subspecies which have been re- 

 garded as species. That the latter view can not be maintained is evi- 

 dent from the existence of a small minority of individuals in which the 

 features of the respective types are found to be wanting or mingled. 

 The persistence of these forms is, however, so evident, that they should 

 take distinct rank in our system. Their definitions are as follows : 



Frontoparietal crests approximated, parallel, not produced; postorbital crests long; 

 no snpratympanic crest ; head 4 to 4.5 times in length B. I. foivleri. 



Frontoparietal crests parallel, not well distiugnished posteriorly on account of the 

 abrupt elevation of the occiput; postorbitals long; no supratynipanic; head 4.5 

 to 5 times /.'./. woodhoiisei. 



Frontoparietal crests divergent, not much produced, and well distinguished behind; 

 postorbitals short; supratynipanic wanting or short; head 4 to 4.5 times in 

 length , B. ]. americav us. 



Frontoparietal crests divergent, prodnced into a knob behind the short postorbitals; 

 snpratympanic well developed; head 3.5 to 4 times in length.. .B. I. JenUf/inosiis. 



The B. I. americanus is the central form from which the others radiate. 

 The B. I. lentiginosus, as the characteristic type of the Austroriparian 

 region, has characters most divergent from the others. The peculiar 

 form B. l.fowleri of the N'ortheast is connected with tlie other types by 

 the B. I rcoodhousei of the Rocky Mountains. Tlie latter is the most 

 difficult to separate from the eastern B. l. americanus, though its typ- 

 ical representatives are quite distinct. 



