AMPHIBIANS 149 



bi Tail dorsally thin and flattened 2. Dicamptodon. 



hi Tail dorsally thick and glandular 3. Amby stoma. 



1. Rhyacotriton Dunn. Lungs very small; ypsiloid cartilage 

 aborted; nasal bones absent: i species. 



R. olympicus Gaige. Color black above; length 125 mm.: Olympic 

 Mountains, Washington, in mountain streams. 



2. Dicamptodon Strauch. Lungs and ypsiloid cartilage normal: 

 nasal bones present: 2 species. 



D. ensatus (Eschscholtz) {Chondrotus tenehrosus Baird & Girard). 

 Body very large and massive; legs stout; color reddish brown, mottled 

 above; length 250 mm.; tail 100 mm.; costal grooves 12, obscure: coastal 

 region of Pacific slope, from central California to British Columbia. 



D. aterrimus (Cope). Body stout; color black above, plumbeous 

 beneath; length 160 mm.; costal grooves 12: Montana. 



3. Ambystoma Tschudi. Lungs and ypsiloid cartilage well devel- 

 oped; premaxillary fontanelle small or wanting; nasals present: about 

 18 species, all American except A. persimilis Gray of Siam; about 12 

 species in the United States. These salamanders can float in water 

 without swimming movements, because of their lungs. 



Key to the United States Species of Ambystoma 



ai Species east of the Rockies. 



bi Costal grooves 10 to 12; vomerine teeth in i, 3 or 4 

 patches, running across the mouth behind the nares 

 (Fig. 69). 

 Ci Two plantar tubercles (Fig. 68) present. 



di Costal grooves 10 A. talpoideum. 



do Costal grooves 12 A. trigrimim. 



C2 One plantar tubercle present or none, 

 di Costal grooves 11. 



ei Body with black and white bars A. opacum. 



en Body black with 2 rows of yellow spots A. maculatum. 



do Costal grooves 12; toes very long .4. jefersoniamim. 



h-2 Costal grooves 14; teeth in 2 patches not extending 

 behind the nares (Fig. 70). 

 Ci Definite color markings in form of cross bars. 



di Body black with narrow white cross lines A. cingulatum. 



d-i Body dark brown with broad yellow cross bars A. annulatum. 



c-i Xo definite cross bars present .4. microstomum. 



02 Species in the Rockies and far-west. 



bi Four phalanges in the fourth toe of hind foot. 



Ci Body mottled with black and yellow; no dorsal stripe. ^4. tigrinum. 



Co A light dorsal stripe present A. macrodactylum. 



bo Three phalanges in the fourth toe of hind foot. 



