66 MONOGRAPHIA 



occasionally found in society, by the central spaces to the 

 lateral fasciae of the abdomen, being milky white, while in 

 the former they are varied from dull yellow to a chestnut. 

 It is also a widely spread species, having been brought 

 home by the expedition under Captain Back in 1836. 



3. DOCOPHORUS SEMISIGNATUS. (Louse of the Raven.) 



Plate I. Fig. 5. 



Milky white, shining, and hairy ; head large, very broad, 

 subcordate, with a colourless depression in front ; abdomen 

 with the first seven segments, having a conical black fasciae 

 on each side; femora, with two black bands. 



Docophorus semisignatus ? Burmeister Handbuch ii. pt. ii. p. 424. 



Head large, very obtusely triangular or subcordate, with 

 a colourless depression in front, and two black diagonal 

 bands from the antennae to the occiput; eyes small, black; 

 antennae, with the first two joints very large, the last three 

 small, equal and cylindrical, with a black spot on each 

 side ; trabeculae large, thick, obtuse ; prothorax transverse, 

 angles rotundate; metathorax about the width of the head, 

 sub-triangular, lateral margins black ; abdomen very broad, 

 nearly orbicular ; the first seven segments with a lateral, 

 conical, black fascia, each having a white centre, last two 

 all white ; legs thick ; femora with two black bands ; tibiae 

 with a black annulus at the apex. Length 1. 



Found on the Raven (Corvus Corax), and communi- 

 cated by that zealous investigator of the Zoology of Ireland, 

 William Thompson, Esq. of Belfast. The great width of 

 the head, and colourless anterior depression, are sufficient 

 to distinguish this insect from D. ocellatus, to which it 

 approaches very nearly ; Dr. Burmeister records the D. se- 



