These frogs are all referred to _M. pygmaeus_, because this is the earliest name available for frogs showing the variation in characteristics displayed by this large series. The characters used by Taylor (1936a, 1940d, 1941a, and 1942b) and Smith and Taylor (1948) to distinguish the various species of _Microbatrachylus_ include color pattern, relative length of the hind limb, presence and position of dorsal dermal folds or pustules, relative size of inner and outer metatarsal tubercles, and the number of palmar tubercles. All specimens from Arteaga have two palmar tubercles; the inner and outer metatarsal tubercles are subequal in size. Furthermore, aside from sexual difference, there is little variation in the relative length of the hind limbs (Table 3). However, many color patterns do exist in the series; each of these color patterns is described below. TABLE 3.--SNOUT-VENT LENGTH EXPRESSED AS A PERCENTAGE OF TIBIA LENGTH IN ANIMALS OF SIX COLOR PATTERNS OF MICROBATRACHYLUS PYGMAEUS. (LETTERS REFER TO THE VARIANTS HAVING THE COLOR PATTERN DISCUSSED IMMEDIATELY BELOW) +------------+-----------+---------+---------+----+--------+ | | | Number | Range | | Twice | | Color | Sex | of | of |Mean|standard| |Pattern | |specimens|variation| | error | | | | | | |of mean | +------------+-----------+---------+---------+----+--------+ | A | Male | 25 |51.4-57.5|55.2| 3.34 | | | Female | 25 |49.3-54.9|51.6| 3.12 | | B | Male | 20 |51.0-57.1|55.4| 2.44 | | | Female | 21 |47.3-54.9|51.2| 3.52 | | C | Male | 6 |54.5-56.2|55.2| .... | | | Female | 6 |50.0-52.9|51.6| .... | | D | Male | 17 |52.9-58.2|55.4| 2.64 | | | Female | 14 |48.5-56.6|52.1| 4.16 | | E | Male | 10 |50.9-56.9|55.1| 3.40 | | | Female | 7 |49.6-54.5|51.6| .... | | F | Female | 2 |51.9-52.6|52.3| .... | +------------+-----------+---------+---------+----+--------+ A.--225 specimens: Dorsum mottled brown and cream, usually with a dark spot between the eyes and one or two dark V-shaped marks with the apex anteriorly on the back; 55 of these have a narrow cream-colored line from the tip of the snout to the vent and thence onto the posterior surfaces of the thighs. All are pustulate above; in most specimens the pustules form no pattern, but in some they tend to form a V in the scapular region. B.--41 specimens: Dorsum pale tan or cream-color with brown mottling on flanks; a brown interorbital bar and a brown chevron in scapular region. Dorsum irregularly pustulate; in some specimens the pustules tend to form a V in the scapular region.