13. PHRYNOSOMA 417 



lining of the esophagus and the stomach seems to be pecu- 

 liarly resistant. 



"A common habit, seen in about twenty-five per cent of 

 specimens, is that of wagging the tail when irritated. Inci- 

 dentally, this habit is quite general among reptiles. Many 

 non-venomous snakes vibrate the tail when surprised. Often 

 they are mistaken for rattlesnakes, as the sound of a rapidly 

 vibrating tail in leaves or dead grass is not unlike the warn- 

 ing of Crotalus. 



"The male horned lizards sometimes fight each other in 

 hot weather, — if confined closely. This fighting seems to 

 be rather harmless, consisting mainly of vigorous puffing and 

 blowing. The writer once observed a large male dragging 

 around a smaller one holding its tail in his mouth. 



"Horned lizards, unlike other lizards, do not have the 

 power to break off the tail, when that member is grasped. 

 In fact, a convenient method of capture is to seize the ani- 

 mal by its tail. 



"The Texas form may at times greedily lap up water, 

 but seems to depend mainly on drops of dew on the vegeta- 

 tion. This habit is shared by the other members of the 

 genus. 



"In North-central Texas, the horned lizards disappear 

 with the first cold burst, which comes on usually between 

 the middle of September and the first of October. Occa- 

 sional specimens, especially very young forms, may be found 

 as late as the first of December; but the majority are gone 

 for the winter, after the first "norther," despite the many 

 warm days which may follow." 



"Unlike the desert species of the genus, these forms are 

 far more active in the middle of the forenoon than during 

 the hottest part of the day, which lasts from about noon to 

 the middle of the afternoon. In the forenoon, Phrynoso- 

 mas are actively feeding, and the collector finds them read- 



