ART. 20 TAXONOMY OF BITING LICE EWING 15 



In certain repects Dennyus and Eurewm are primitive or general- 

 ized, having the primitive characters as follows: 



1. A well developed and clearly separated mesothorax. 



2. A double pair of eyes. 



3. Simple and generalized tarsi, devoid of important reductions 

 or modifications. 



4. A simple and generalized type of male genital armature. 

 On the other hand, the genus is characterized by a much larger 



number of specialized characters, among them beino-; 



1. Last two segments of antennae formed into a subglobose struc- 

 ture. 



2. Antennae situated in very deep fossae. 



3. Temples of head modified into a shape different from practi- 

 cally all other genera of Mallophaga and characteristic of the genus. 



4. Anterior femora greatly modified by inflation. 



5. Prothorax specialized in having lateral, expanded, spiniferous 

 lobes. 



6. Prosternal plate abnormally developed and overchitinized. 



7. Posterior femora and some of abdominal sternites f>rovided 

 with patches of setae. 



8. Pleurites of abdomen bear marginal spines. 



9. Tibiae show marked evidence of incipient segmentation by the 

 development of a transverse suture. 



All points considered, Dennyus and Eureum should be regarded 

 in the same light as many other mallophagan genera. They evi- 

 dently are ancient genera with many highly specialized and cor- 

 related characters, yet at the same time they possess a few very 

 primitive ones. They in all probability represent a complex that 

 has had a paralleled phylogeny with their hosts, the swifts. 



THE STTEMATIC POSITION OF THE GENUS HIRUNDOECUS, NEW GENUS 



Let us now take these same 13 characters that have been consid- 

 ered in regard to Dennyus and Eureutn and observe them in Hirun- 

 doecus. We have : 



1. Mesothorax greatly reduced, inconspicuous, yet showing a 

 dorsal suture between it and metathorax. 



2. Eyes wanting. 



3. Same as in Dennyus and Eureum. 



4. Genital armature showing slight modification from generalized 

 type. 



The adaptive or specialized characters follow : 



1. Same as in Dennyus and Eureum. 



2. Fossae even deeper than in Dennyus and Eureum. 



3. Temples considerably modified from usual shape. 



4. Anterior femora similar to others. 



