li)16 ] Camp: Amphibians and Reptiles 515 



adversary, but do him no damage except sometimes to turn him upon 

 his back ; lie may then struggle for some time with one fore leg vibrat- 

 ing vigorously in the air and the other pawing for a foothold in the 

 ground before he can right himself. 



The males court their mates by biting them gently around the edges 

 of the shell. During copulation the male stamps his hind feel and 

 utters a mechanical grunt with the head hooked over the end of the 

 plastron and the mouth half open. 



Stephens (1914, p. 135) writes that teeth marks are sometimes seen 

 on shells of living tortoises and believes that the shells "generally 

 prove too hard for the coyotes." The younger tortoises are soft-shelled 

 and delicate. They probably fall prey in numbers to raptorial mam- 

 mals and birds. The old ones are a favorite delicacy among Indian 

 and Mexican section-hands who live with their families along the rail- 

 road lines. Some tortoises kept as curiosities at Needles on a grass plot 

 in front of the Santa Pe hotel are thought to have been gradually de- 

 pleted by the inroads of the Indians, many of whom lounge about the 

 place. 



Dipsosaurus dorsalis Baird and Girard 

 Desert Iguana 



Pour desert iguanas (nos. 5499-5502) were taken in the vicinity of 

 Blythe Junction. In two specimens the rostral plate is separated from 

 the nasals by one row of scales, and in the other two individuals by 

 two rows. The femoral pores are 18 in two thighs, 21 in four, and 22 

 in one; being 18 right : 18 left once, 21 :21 twice, and — :22 once. 



The ground color varies slightly from light grayish to yellowish. 

 One specimen has wide, brown reticulations enclosing lighter spots on 

 the sides and back. A smaller example has narrow brown dots and 

 dashes in place of the broad reticulations. 



The total length of the largest individual is 360 millimeters ; the 

 tail is partly regenerated and measures 242 millimeters. 



These round-nosed, large-tailed lizards are fairly common in the 

 low plain environment in the sandy tracts south of Blythe Junction, 

 and in the washes traversing the alluvial slopes about the Turtle Moun- 

 tains. They appear to avoid rocky ground, being absent from the hill- 

 sides and mesas. They are shy when approached and run swiftly, with 

 tail slightly raised, to the shelter of a bush, or into a chipmunk's or 

 kangaroo-rat's burrow. When wounded they puff themselves up till 



