190 BULLETIN 160, UNITED STATES NATIONAL MUSEUM 



With the exception of the generic names that are based on Linnaean 

 species from Europe, the synonyms of the genus Rana here enumerated 

 are restricted to those based on New World species. 



There are at least six distinct species of the genus Rana on conti- 

 nental Mexico. The largest of these is the well-known North Ameri- 

 can bullfrog {R. catesbeiana) , which is here for the first time recorded in 

 Mexico. The wide-ranging leopard frog {R. pipiens) seems to be the 

 most abundant rana in Mexico. One South American species, R. 

 palmipes, reaches its northern limit in Vera Cruz. A Mexican relative, 

 R. tarahumarae, of the Pacific coaSt yellow-legged frog (R. boylii) has 

 been found in the high sierras of western Chihuahua. R. montezumae 

 undoubtedly possesses the most peculiar color pattern of all Mexican 

 ranas, and notwithstanding its characteristic appearance nothing has 

 been published in regard to its life history, and all that is known of its 

 habitat is that it frequents the lakes in the Valley of Mexico. The 

 rarest of all Mexican frogs in collections is one which Boulenger named 

 Rana pustulosa. 



All known species of the genus Rana, except one, deposit their eggs 

 in the water, where they develop into tadpoles. The single exception 

 of this general habit is a frog (R. opisthodon) that occurs on the 

 Solomon Islands, and this species lays its eggs on land in moist crevices 

 of rocks close to water. These eggs develop directly into frogs with- 

 out any aquatic tadpole stage. The regular larval stage and subse- 

 quent metamorphosis are hurried through within the egg. Tho buccal 

 apparatus of the larvae of these ranas is quite characteristic for each 

 species, and many of them can be recognized in life by their color 

 pattern. The mouth disk is devoid of horny teeth in some species. 

 In others there are more than the normal number of rows. The tad- 

 pole of R. catesbeiana may have as many as three rows of horny teeth 

 in the upper and in the lower jaws. 



KEY TO MEXICAN SPECIES OF RANA 



1 . No trace of dorso-lateral glandular dermal folds 2 



Dorso-lateral glandular dermal folds present 3 



*?. Tympanum distinct, with or without small asperities, its trans- 

 verse diameter two-fifths to one-half that of eye; upperparts, 

 including top of head, brown or olive, marked with irregular 

 blotches, or small black spots, or numerous dots; limbs with 

 irregular dark crossbars; abdomen white; throat and chest 

 either white or mottled with brown; limbs mottled with grayish 

 brown; skin of upperparts either smooth or with small 

 pustules; a feeble curved glandular fold from eye to shoulder, 

 but no dorso-lateral glandular fold; the hind limb being carried 

 forward along the body, the tibio-tarsal joint reaches to or 

 nearly to end of snout; tarsal fold distinct or indistinct; distance 

 from snout to vent 1% to 2 times length of tibia; tips of toes 

 swollen into small disks; a broad web between the toes; outer 

 metatarsals separated nearly to base; inner metatarsal tubercle 



