124 MONOGRAPHIA 



with a transverse conical pitchy fascia on each side, marked 

 with two circular white spots united by a line ; legs pale 

 yellow, thick and strong ; femur and tibia with a fuscous 

 annulus at the apex. Length 1 . 



I have found this species upon the Rook (Corvus frugi- 

 legus), but by no means plentiful. Dr. Burmeister states it 

 is also found on the Raven (Corvus corax). I received a 

 specimen from J. C. Dale, Esq. of Glanvilles Wotton, 

 Dorset, which he informs me was found on the Blackbird 

 (Turdus merula). This however had most probably been 

 only a* temporary sojourner ; Mr. Stephens in his Syste- 

 matic Catalogue of British Insects mistakes the Menopon 

 en^y sternum of Burmeister for this species, at least I sus- 

 pect so, from his Synonyms, with one exception, referring 

 to the former, and not to the Nirmus argulus of Nitzsch. 



16. NIRMUS VISCIVORI. Denny. (Louse of the Missel 

 Thrush.) 



Plate VII. Fig-. 7. 



Pale stramineus, shining and smooth ; head fulvous yel- 

 low, with a broad semicircular chestnut fascia on each side ; 

 sutures of the abdomen strongly marginate, lateral margin 

 fulvous. 



Head sub-cordate, with an oblong depression in front, 

 and a transverse impressed line connecting the lateral 

 fasciae; vertex concave, lateral margin slightly sinuate before 

 the eyes, with a long stiff hair from each temporal lobe, 

 base truncate ; antennae rather thick, the second joint 

 somewhat obconic ; trabeculae conical ; prothorax trans- 

 verse ; metathorax wider than the head, subtriangular, 

 lateral margins oblique, posterior acutely produced in the 

 centre and setose ; abdomen oblong oval, sutures of the 



