28 
University of California Publications in Zoology [Vol. 27 
Secondary Sexual Characters 
In most species of Salientia in California the sex can be ascertained 
by external examination alone (see figs. J-L). The sexing of most 
of the specimens used in the tables of measurements was accomplished 
in this way, using the following criteria : (1) In Scaphiopus and Bufo 
the presence of dark-colored nuptial excrescences (asperities) on the 
first and second digits of the hand in males. These, while best devel- 
oped during the breeding season, are present in some individuals 
captured at other times of year; the darkened vocal sac (when pres- 
ent) is also a usable character. (2) In Hyla, the presence of loose, 
thin, dark-colored skin (vocal sac) on the throat region of males. (3) 
Fig. J. Eight fore limb of Bufo boreas halophilus, male (no. 5696, M. V. Z.), 
showing dark-colored ‘ nuptial ’ excrescences developed on inner surface of digits. 
These are absent in females and immature males and reduced in adult males in 
the non-breeding season. 
Figs. K, L. Eight fore limb of Bana aurora draytonii, male and female (nos. 
7151, 7150, M. Y. Z.), showing short first digit with enlarged ‘nuptial’ excrescence 
and greater development of forearm in male, and elongate form of first digit in 
female. 
In Bana, the presence of a nuptial excrescence and the thickened form 
of first digit on hand in males ; the first digit of females is smoothly 
tapered. Prior to using these criteria, several individuals of each 
species were sexed by dissection and direct examination of the sex 
organs. Many females contained eggs in various stages of develop- 
ment or resorption. After laying is completed, the oviducts remain 
swollen for some time and this condition facilitates determination of 
‘spent’ females. In many of the earlier works on amphibians (includ- 
