186 THE GROUSE IN HEALTH AND IN DISEASE 



they occur in small groups attached to the base of the after-plume and 

 between it and the shaft of the plume. The specimen figured was on 

 one of the feathers from the flank. (See PI. xvii. Fig. 4.) 



The eggs are elongated, some three or four times as long as they are 

 broad. They are fixed by some adhesive secretion at the end corres- 

 ponding to the hinder end of the embryo they shelter. At the other 

 end is a well-marked cap or operculum which always points to the free 

 end of the feather. The beauty of the marking on the egg-case is 

 shown best in another but allied genus, 1 and we figure one, which 

 we found 2 on the feathers of a partridge. Under the pressure of a 

 coverslip the egg-case gradually ruptured along a circular line below 

 the well-marked thickened edge or rim of the cap. The contained egg 

 then began to emerge, carrying off with it the cap. The resemblance 

 of this structure to a cap was emphasised by the long process which 

 stands out like a feather borne on its apex. The eggs of the broad bird- 

 louse of the Grouse show the network markings less well, but they are 

 conspicuous on the cap, which bears a long tapering filament, longer 

 than the egg itself. These markings also occur just below the cap, but 

 fade away towards the fixed end. The general appearance of the eggs 

 on the after-plume is shown in PI. xvii. Fig. 3. They were found on 

 the 27th July 1908, and they seem to be laid throughout the summer. 



There is no metamorphosis, the young leaving the eggshell as 

 miniatures of their parents. 



II. Nirmus cameratus, Nitzsch. 

 The Narrow Bird-louse of the Grouse. 



This insect seems to have been first named by Nitzsch 3 in the 

 year 1818, but with no description. It is figured and described, 

 and a bibliography is given by Denny 4 under the name of Nirmus 

 cameratus. Denny found it on the Red Grouse, the Black Grouse, 

 "and I expect also upon the Ptarmigan." Grube describes it in 

 Middendorf's " Siberian Travels " as existing on the Willow Grouse 5 

 and the Ptarmigan, thus confirming Denny's surmise. 



This narrow bird-louse is mentioned in Giebel's article 7 on bird- 

 lice at Halle, and described and figured in his great monograph. 8 

 Piaget in his " Les Pediculines," states his conviction that N. cameratus 

 is specifically identical with the N. quadrulatus of Nitzsch, from the 

 Capercailzie. This opinion is also held by Kellogg. 10 



1 Menopon. 



2 This egg is almost certainly the egg of Menopon pallescens, Nitzsch. 



3 Germar's Magazin der Entomologie, Halle, iii., 1818, p. 291. 



4 "Monographia Anoplurorum Britannirc," London, 1842, p. 112. 



5 Jst'iopus albus. , Lin. =L. sub afpinus, Nils. 

 8 Lagopus mutus, Leach = L. alp in us. 



7 "Zeitsch. Ges. Naturwiss.," xxviii., 1866, p. 370. 



8 Insecta Epizoa. 8 Tetrao urogallus. 

 10 Wytsman's Oerura Inseclorum, 66th Fasc. Mallophaga. 



