264 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



great amounts of surface water. Prior to that time, one active adult 

 was dug from moist ground in the riparian association at a depth of 

 six feet during excavations for a swimming pool. 



One hundred and fifty-three larvae, similar in coloration to that 

 described by Stebbins (1951, p. 46) from near Flagstaff, Arizona, were 

 seined from a pothole approximately 10 feet in diameter on July 16, 

 1957, at 7800 feet. Of these, 36 measured 35-45 (x 42.2) mm. snout- 

 vent, 32-39 (35.8) mm. tail length. In the laboratory, 25 were kept 

 for 28 days, 5 to a gallon jar. At the end of this period, 5 specimens 

 had died, 14 had fully transformed, and 6 still possessed well-developed 

 gills and larval body form. Body proportions of these specimens 

 reveal greater size in the recently metamorphosed individuals (fig. 5). 

 During captivity the larvae continuously gulped air at the water 

 surface, something they had not been doing when collected. 



On July 27, 1957, larvae equal in size to those previously captured 

 at 7800 feet were taken from an arroyo 500 feet lower at the mouth of 

 the same canyon and nearly one mile distant. A week of heavy rain 

 that flooded the first locality filled the previously dry arroyo and 

 presumably carried larvae to the new locality. 



Five large larvae and one adult were collected in the pothole at 

 7800 feet, July 3, 1958, prior to the onset of heavy summer rainfall. 

 The pond was 15 feet wider at this time than previously. About 

 20 other A. iigrinum of similar size could be seen surfacing and gulp- 

 ing air. The majority of these had normal larval gills and body 

 form, but several had reduced gills. No other adults were observed 

 although several were taken in ponds later in the summer. The 

 collected larvae were light olive green dorsally with scattered dark 

 spots. Two transforming specimens had light lateral reticulations 

 on the tail; theu" venters were unmarked. These five larvae and 

 six others from a pool at 7000 feet are of similar coloration and pro- 

 portions. They have relatively longer tails than transformed speci- 

 mens of similar body size (fig. 5). 



The above data suggest that larval development requires at least 

 two years in some populations of ^. t. nebulosum in the Zunis. First 

 proposed by Burger (1950b), this life history pattern does not apply 

 necessarily to all Zuni larvae, for shallow pools at 7300 feet examined 

 July 3, 1958, contained small larvae similar in size to the first-year 

 individuals taken in 1957. Spatial isolation of larval size groups 

 is not surprising when one considers the predacious nature of these 

 salamanders. The tadpoles of Hyla arenicolor and Bufo woodhousei, 

 although abundant in the area, rarely were found m the same pools 

 with A. tlgmium. Food habits of tiger salamander larvae during the 

 anuran breeding season demonstrate why this is so (fig. 6). 



