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three times, with seemingly no perceptible effects, it was taken out and 

 placed in a cage with a rattlesnake, where it was bitten twice, and within 

 the space of two hours was dead. A second rat, after an absence of a few 

 days, was put in with the heloderma and was bitten three times ; once upon 

 the fore leg, and once upon the tail, and again through the lower jaw. The 

 first two bites occurred before nine o'clock in the morning, the third about 

 one in the afternoon. At four o'clock the same day the rat seemed all right, 

 with the exception of being cowed and having a desire to get as far from 

 the lizard as possible. The next morning, upon observation, the rat was 

 found dead, and when picked up a greenish fluid ran out of its mouth. 



The heloderma, when undisturbed, is a harmless individual, and at no 

 time was its biting voluntary. But when disturbed he elevated his head 

 with mouth open, giving forth the aspirate sound of hah, and if at this time 

 any thing is placed within his open mouth, the jaws immediately close 

 upon it. The biting is simply holding fast for a few minutes. There are 

 no fangs in the upper jaw, as in the rattlesnake, and if there be any poison 

 it must be from the ordinary saliva and depends upon the degree of irrita- 

 tion of the animal. 



Judging from the actions of the two rats bitten, one by the snake and the 

 other by the lizard, we believe the poison in the two reptiles acts differ- 

 ently. From the death struggles of the one bitten by the rattlesnake there 

 appears to be a paralysis of the respiratory organs, while from the stupor 

 which appeared to take hold of the other, we judge in that case to be a 

 paralysis of the circulatory organs. 



Some ohservatioxs ox photomicrograimiv. By D. W. Dennis. 



Contributions to a knowledge of the grain toxoptera (toxoptkra 

 GRAMiNi'Mi. By F. M. Wekster. 



