ORDER PARASITA. 151 



With the exception of a single species, that of the dog, 

 all the others are exclusively found on birds. Their head is 

 generally large, sometimes triangular, sometimes crescented, 

 and often has angular projections. It differs sometimes in 

 the two sexes, as well as the antennae. I have observed in 

 many, two simple eyes, approximating on each side of the 

 head. According to the observations communicated to me 

 by M. Savigny, these insects have jaws, with a very small 

 palpus on each of them, and are ctmcealcd by the under lip 

 which has also two organs of the same sort. They have, 

 besides, a species of tongue. 



M. Leclerc de Laval, has told me, that he has seen in 

 their stomach, particles of the feathers of birds, and believes 

 that this constitutes their only nutriment ; Degeer, how- 

 ever, assures us, that he found the stomach of the ricinus 

 fi'ingUlcB filled Avith blood, with which the insect had just 

 gorged itself. It is also known that these insects cannot 

 continue to exist any length of time upon dead birds ; they 

 are then seen to crawl uneasily over the feathers, particu- 

 larly over those of the head and the neighbourhood of the bill. 



Redi has also represented a great number of their species. 



Some have the movith situated near the anterior extremity 

 of the head. The antennse are inserted at the side, far from 

 the eyes, and are very small.* 



In the others the mouth is almost central. The antennse 

 are situated very near the eyes, and their length equals 

 almost the half of that of the head.-f- 



* Pediculus stervicB hirundinis. Linn. D. G. Insect, VII. iv. 12 ',—pedi- 

 culus corvi coracis. Linn. D. G. ibiil. 11; — Ricinus fringillcB, (D. G.) ibid. 

 5, 6, 7 ; — 2^^diculus tinnunculi. Panz. ibid. XVII. 



-j- Ricinus gallincBjD. G. ibid. 15; on the hen partridge and pheasant; 

 — R. emberizoe. D, G. ibid. 9 ; - R. Mergi, D. G. ibid. 13, 14 ; — 11. Canis, 

 D. G. ibid. 16; — Pediculus pavonis, Panz. ibid., xix. Lat. Hist. Nat. des 

 Fourm. 589, xii. 5. See again, Panzer pi. xx., xxiv. His pediculus 

 ardecEy xviii., appears to be the same as the ricinus of the diver of Degeer, 

 iv. 13. 



