_Description and Variation._--The dorsal color pattern is highly variable. The various permutations of the X-shaped scapular mark and dark sacral marks differ proportionately in different samples. The variation in color pattern in 12 samples is summarized in Table 2. In samples from the southern part of the range (southern Nicaragua and Guanacaste Province, Costa Rica) more (40-93%) individuals have the lateral stripes extending to the groin than in northern samples (0-42%) from southern México and Guatemala. Likewise, the percentage of specimens lacking bars on the shanks and a dark interorbital bar is higher in the Costa Rican samples than elsewhere in the range. The X- or )(-shaped scapular markings and /\- or / \-shaped sacral markings are most prevalent in northern samples, whereas to the south the dorsal markings are more commonly arranged in a pattern of paired lines, which usually are discontinuous and usually extend posteriorly only to the sacral region. Thus, the color pattern in _H. m. underwoodi_ in the southern part of its range shows trends towards the pattern characteristic of _H. m. microcephala_. Intergrades between these two subspecies have been discussed in the account of the nominate subspecies. Table 2.--Variation in Color Pattern in Hyla microcephala underwoodi ========================================================================== Population | N | Shanks || Interorbital || Dorsolateral | | | || bar || stripe | | |-------------||----------------||--------------| | | Bars |Flecks|| Present| Absent|| Groin| Sacrum| -------------------------------------------------------------------------- Oaxaca: | 27 | 22 | 5 || 27 | 0 || 0 | 27 | Donají-Sarabia | | | || | || | | | | | || | || | | Tabasco: | 55 | 46 | 9 || 55 | 0 || 0 | 55 | Teapa-Villahermosa| | | || | || | | | | | || | || | | Guatemala: | 51 | 51 | 0 || 51 | 0 || 17 | 34 | La Libertad | | | || | || | | | | | || | || | | Guatemala: | 32 | 32 | 0 || 32 | 0 || 0 | 32 | Finca Chamá | | | || | || | | | | | || | || | | Guatemala: | 31 | 31 | 0 || 31 | 0 || 14 | 17 | Puerto Barrios | | | || | || | | | | | || | || | | Honduras: | 13 | 13 | 0 || 13 | 0 || 9 | 4 |