39+ 3. IGUANIDM 



brought on by the night. The eyelids, on being sectioned 

 were found to be highly vascular and to contain large blood 

 sinuses. Especially was this true of the upper lids. No 

 duct was found and it seems probable that the blood is forced 

 out by the rupturing of a vessel. H. L. Bruner (1907), in 

 a paper on the 'Cephalic Veins and Sinuses of Reptiles,' gives 

 the best explanation yet advanced. He says, in speaking of 

 Phrynosoma, 'It is not improbable in this case that the mech- 

 anism for elevating the blood-pressure is used as a fright 

 mechanism. Such a function, however, is not sufficient to 

 explain the wide distribution of the mechanism. On the 

 contrary, it is probable that the flooding of the cephalic 

 sinuses for frightening enemies is at best only a secondary 

 use which has been acquired by relatively few forms.' 



"These lizards show great aversion to dogs. When an- 

 gered by one, the lizard presents a very bristling appearance 

 by elevating the enlarged scales of the back, opens its mouth 

 and gives a hissing noise by quickly expelling the air from 

 the lungs. At such times it stands well upon its legs and 

 puffs itself up to nearly twice its natural size. A blainvillei, 

 when first caught, often hisses at any moving object. 



"At sight of a snake, however, instead of standing its 

 ground and attempting to frighten the intruder, it generally 

 seeks to escape. A small California ring-neck snake {Dia- 

 dofhjs amab'dis) when placed in a cage containing several of 

 these lizards, created no little excitement. When the ex- 

 citement had somewhat quieted down, two of the lizards be- 

 came courageous enough to take a nip at its tail. This would 

 in a measure seem to corroborate the statement that has been 

 made that these animals attack a snake when cornered. 



"The food consists principally of ants, although the 

 smaller beetles and flies seem to be eaten with relish. Even 

 a large Jerusalem cricket does not daunt one of these liz- 

 zards, for it seizes it by the head and, not being able to swal- 



