Book-lice and Bark-lice ; Biting Bird-lice 119 



C. Forehead evenly rounded, without lateral swellings; antennae projecting 



slightly beyond border of the head COLPOCEPHALUM. 



CC. Forehead with strong lateral swellings. 



D. Mesothorax separated from metathorax by a suture TRINOTON. 



DD. Meso- and metathorax fused; no suture L^MOBOTHRIUM. 



BB. Ocular emargination absent or very slight. 



C. Sides of the head straight or slightly concave, with two small laterally 



projecting labral lobes PHYSOSTOMUM. 



CC. Sides of the head sinuous; forehead without labral lobes. 



D. Ocular emargination filled by a strong swelling; sternal markings 



forming a quadrilateral without median blotches NITZSCHIA. 



DD. Ocular emargination without swelling, hardly apparent or entirely 

 lacking; median blotches on sternum. 



E. Very large; with two-pointed appendages on ventral aspect 

 of hind head; anterior coxae with very long lobe-like append- 

 ages ANCISTRONA. 



EE. Small or medium; without bi-partite appendages of hind head. 



MENOPON. 



The Mallophaga most likely to come under the observation of people 

 not collectors of birds are the species which infest domestic fowls and mam- 

 mals, and the following few descriptions and figures of particular species 

 are therefore limited to such kinds. 



The most notorious member of the order is the common chicken-louse, 

 Menopon pallidum (Fig. 146). It is of a pale straw-yellow color, from 

 i mm. (% l j in.) to 1.5 mm. 

 in length, and is an un- 

 usually swift and active 

 little pest. Other Mallo- 

 phaga infesting chickens 

 are Goniocotes hologaster, 

 recognized by its squarish 

 head with angulated 

 temples, and Lipeiirus 

 variabilis, 2 mm. (-fa in.) 

 long and slender, with dis- 

 tinct black markings on 

 the otherwise smooth, 

 white body. 



Ducks are infested by 

 several species. Com- F _, 



mon among them is the FIG. 146. The biting chicken-louse, Menopon pallidum. 



little DocophorilS icterodes (After Piaget; natural size, i to 1.5 mm.) 



/T -,. N f ., \ FIG. 147. The biting louse of wild ducks, Docophorus 



fig-M?;* 1 m - \T5 m -) icterodes. (Natural size indicated by line.) 

 long, with head curiously 



expanded and rounded in front, darkish-red head, and thorax with darker 



