FEATHER LICE iqg 



which Pediculus humanus, the human louse, is a well-known example. The 

 sucking lice, which are found only on mammals, feed solely on blood, 

 their mouth-parts being highly modified for piercing and sucking. 

 The Mallophaga and the Anoplura are classified as suborders of the 

 same order — Phthiraptera — thus showing the relationship between the 

 two groups. The primitive ancestral Mallophaga must have split at an 

 early period into two stocks which evolved on different lines, and which 

 gave rise to the two distinct superfamilies, the Amblycera and Ischno- 

 cera (Plate XXII). The early Mallophaga, especially the Ischnocera, 

 occupied the different ecological niclaes found on the bodies of their 

 hosts, and became specialised and adapted for the characters of each 

 niche. This, as we have seen, meant considerable modifications in 

 the external morphology (Plates XXI and XXIII), involving 

 many superficial distinctions, although the characters of the internal 

 anatomy and basic morphology of the Ischnocera are mostly very 

 similar. This last fact suggests that evolution of the basic Ischnocera type 

 was relatively rapid and took place before their occupation of the 

 different ecological niches, to which they subsequently became adapted. 

 Possibly the primitive birds had a more uniform feather covering, 

 somewhat similar to that of the ostriches and rheas, which did not 

 provide the different ecological niches present in the more recent orders. 

 This is partly confirmed by the Mallophaga of these present-day primi- 

 tive birds which present only one generalised type, none being specially 

 adapted to the neck or wings. The basic similarity of the Ischnocera, 

 in spite of their superficial differences, makes the classification into 

 families difhcult, and the present unsatisfactory arrangement will not 

 be discussed here. 



ORDER PHTHIRAPTERA 



SUBORDER MALLOPHAGA (chcwing lice) anoplura (sucking lice) 



SUPERFAMILY amblycera ischnocera 



For scientific purposes the birds are classified or divided into groups 

 or orders, and those characters which affect the louse, such as the 

 minute structure of the feathers, are generally uniform throughout the 

 order. Consequently the lice which occupy an identical ecological 



