28 



MILLIPEDES 



Fifteen of the birds taken in April were found to have eaten 

 nothing else, and nine tenths of the food of fourteen others was 

 composed of millipedes. 



To most animals, however, millipedes are rendered somewhat 

 unpalatable on account of their tough integument and by the irri- 

 tant exudates secreted by the repugnatorial glands of the Colobo- 

 gnatha, Proterospermophora and Opisthospermophora. The struc- 

 ture of these glands is very similar in all three orders. They are 

 sac-like in shape and each discharges into a lumen which in turn 

 leads to the foramen or opening. Though the glands themselves 

 cannot be compressed, their openings can be regulated by special 

 muscles, while other muscles nearby exert considerable pressure 

 when the animal moves suddenly. In most cases the secretion is 

 exuded fairly slowly from the pores of the glands but in some of 

 the larger tropical forms it can be discharged to a considerable dis- 

 tance in the form of a fine jet or spray. 



Portion of 

 glandular ---_ 

 sac 



Muscle 



surrounding 



duct to exterior 



Foramen 



Fig. 9. Distribution of repugnatorial glands on the segments of 



a millipede Oxidus gracilis. Right, section of an individual gland. 



(After Weber, 1882.) 



The maximum recorded achievement was a double salvo from 

 a Rhinocricus lethifer in Haiti which sent its discharge 28 inches on 

 one side and 33 on the other, the droplets falling fanwise around 

 the body. The repugnatorial fluid of the large tropical species has 

 a strong caustic action and causes blackening on contact with the 



