152 OBSERVATIONS ON BIRDS. 



than a very scanty supply of food.* Nevertheless 

 the forehead and the base of the bill were as much 

 denuded of feathers as in other adult individuals 

 of this species. This case of monstrosity seems an- 

 alogous to that already instanced in the wild rabbit 

 among quadrupeds. f 



It is worthy of remark that this rook swarmed 

 with lice to the most astonishing degree I ever wit- 

 nessed in any animal. Some parts of the plumage 

 were quite alive and covered with them.J It is 

 probable that all vermin increase greatly upon dis- 

 eased animals, owing to their neglecting the ordi- 

 nary means of ridding themselves of them ; and in 

 some cases they may serve to hasten their death, 

 and thus relieve them from their misery. 



JACKDAW. 



JACKDAWS sometimes prove a great nuisance in this 

 part of the country in spring, from their habit of build- 

 ing in chimneys. They often bring such a number of 



* See a representation of the cranium of a rook, having a simi- 

 lar peculiarity in the lower mandible, in one of the vignettes of 

 YarrelVs British Birds, vol.ii. p. 90. 



t See p. 78. 



I These parasites consisted principally of the Colpocephalum 

 subezquale of Nitzsch. See Denny's Anoplura Britannia, p. 213, pi. 

 xviii. fig. 5. I showed some of the specimens to this last gentle- 

 man, who has noticed the circumstance alluded to in the text, in 

 his valuable and beautiful work. With the above species of Col- 

 pocephalum there was also the Docophorus atratus, Nitzsch, but 

 much less abundant. See Denny, pi. iv. fig. 8. 



Corvus monedulu, Linn. 



