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. 



CO. 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 NiTZSCHlA. 



DD. Ocular emargination without swelling, hardly apparent or entirely 

 lacking; median blotches on sternum. 



E. \'ery large; with two-pointed appendages on ventral aspect 

 of hind head; anterior coxa; 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, 

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

 I mm. (3'^ 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 Lipeitrus 

 variabilis, 2 mm. (^^^ in.) 

 long and slender, with dis- 

 tinct black markings on 

 the otherwise smooth, 

 white body. 



Ducks are infested by 

 several species. Com- 

 mon among them is the 

 little Docophonis icterodes 

 (Fig. 147), I mm. (,V i"-) 

 long, with head curiously 

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



Fig. 146. Fig. 147. 



Fig. 146. — The biting chicken-louse, Menopon pallidum, 



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

 Fig. 147. — The biting louse of wild ducks, Docophonis 



icterodes. (Natural size indicated by line.) 



