MEXICAN TAILLESS AMPHIBIANS 211 



tion exists also on immature individuals and has been observed on 

 specimens with a body length as short as 35 mm. More than 20 

 specimens were found that have distinct longitudinal rows of pus- 

 tules on the upper surface of the tibia. On the majority of the adult 

 frogs the skin of the upperparts is granular, with more or less promi- 

 nent longitudinal glandular folds on back between the dorso-lateral 

 folds of the skin. Young frogs and occasional adults have the skin 

 of the upperparts nearly smooth. A dark spot is generally present 

 on each upper eyelid, and in 40 instances a dark spot was noted on 

 the upper surface of the snout. 



The absence of a well-defined streak that extends from end of snout 

 to end of glandular fold behind angle of the mouth on each side of the 

 head above the dark or mottled upper lip is stated by Boulenger in 

 his monograph on the American frogs of the genus Rana to be geo- 

 graphically distinctive for specimens from Arizona, Texas, Mexico, 

 and Central America. This light streak is absent or only distinct 

 from below the eye posteriorly in many of the Mexican specimens. 

 Nevertheless, there are leopard frogs in the United States National 

 Museum from Tamaulipas, Vera Cruz, Guanajuato, Jalisco, Guerrero, 

 and Tabasco that have this light streak as well defined as any indi- 

 vidual from Eastern United States or Canada. The general color- 

 ation of live frogs of this species taken at Cuatotolapam in Vera Cruz 

 is described as follows by Ruthven:®^ 



Ground color of upper parts dark brownish olive, occasionally speckled with 

 bright green; stripe on canthus rostralis and dorsal spots black or blackish, the 

 latter margined with greenish; stripe along upper lip light greenish yellow, fre- 

 quently much broken up; dorso-lateral glandular fold light greenish yellow to 

 orange brown; belly white. 



The length of the hind limb has very little diagnostic value. In a 

 series of 50 individuals, 10 were found in which the tibio-tarsal joint 

 reached to the middle or anterior margin of the eye, when the hind 

 limb was carried forward along the side of the body, 15 in which it 

 reached to between the eye and the end of the snout, 17 to the end of 

 snout, and 8 beyond the end of the snout. 



Noble ^^ has published the following comments on a small series of 

 frogs that are referred to Rana austricola and that were collected by 

 C. R. Halter in Nicaragua: 



The variation in color is not limited to an intensif.ying or fading of the tones. 

 There is also a slight variation in pattern. The spots on the back may be more 

 or less confluent. In the smallest and the largest specimens in the collection the 

 spots have been extended to form an unbroken but irregular streak on each side 

 of the back. Each pair of spots may be confluent in a transverse direction, but 

 it is more common for the spots in each longitudinal row to run together. There 



M Ruthven, A. G., Zool. Jahrb. (Syst. Abt.), vol. 32, pt. 4, pp. 305, 306, 1912. 



w Noble, O. K., The amphibians collected by the American Museum Expedition to Nicaragua in 1916. 

 Bull. Amer. Mus. Nat. Hist., vol. 38, art. 10, p. 316, 1918. 



