372 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxvii. 



clearly defined generic groups.' As it is, every new lot of specimens 

 which comes in changes one's idea of the existing genera, making very 

 evident the great danger in a too rapid increase of generic divisions. 

 Species are now pouring into the collections in great numbers. Where 

 large series from all over the world can be gathered together, there, 

 within the next few years, must be accomplished the total recasting 

 of the whole group on largeh" new and original lines. Logically this 

 should be done at St. Petersburg, where the types of Koh^iati and a 

 large additional collection are to be found under the care of our most 

 experienced siphonapterologist, and to him we relegate this work, 



SYSTEMATIC ARRANGEMENT AND DESCRIPTION OF AMERICAN 



SPECIES. 



Order SIPHONAPTERA Latreille. 



1798. ScHELLENBERG, Helvetische Entom., I, p. 15 {Ropltoteira Y)t.). 



1801. Lamarck, Syst. d. Anim. s. Vert., p. 313 {Ajdera -pt). 



1805. Latreille, Hist. nat. des Crust, et des Insect., XIV {iSuctoria, preoc. ). 



1825. Latreille, Fam. nat. du Regne Animal (Siphonaptera) . 



1826. KiRBY and Spence, Introd. to Entom., IV {Aphaniptera) . 



1840. Westwooo, Introd. to Mod. Class, of Ins., II, p. 488 {Aphmnptera) . 



Body of adult, except in some gravid females, strongly compressed. 

 Thorax composed dorsallj^ of three separate, entire, simple, subequal 

 sclerites. 



Mouth parts suctorial, consisting of stylate hypopharynx and mandi- 

 bles resting between 1-13 jointed labial palpi; outside of these are 

 usually laminate maxilhe with four-jointed palpi; labrum and clypeus 

 not distinctly separated. 



Eyes usually present as simple pigment masses in a chitinous frame- 

 work on anterior border of antennal groove. 



Antenna immersed in grooves, three-jointed, the third joint with 

 usually 9 more or less completely separated pseudojoints. 



Wings entireh' al)sent. Metanotum on either side with a rounded 

 epiphysis which is connate Avith the first abdominal segment. 



Tarsi live-jointed. The coxa is usually the longest ioint of the leg 

 and the trochanters are well developed. The middle and posterior 

 coxfB usually have a foliaceous epiphysis on posterior border. 



Alimentary" canal composed of a slender oesophagus, a suboval 

 proventriculus which is lined with numerous chitinous ridges which 

 may project as free teeth, an elongate saccate stomach at the base of 

 which ai'e four slender malpighian tubules, and a rectum provided 

 with tracheated glands. 



Larva footless, with a well-developed head which possesses biting 

 mandibles, rudimentary maxilla^, a well-formed labrnm, and three- 

 jointed antennsi?. 



Pupa inactive, but with free legs, and sometimes at least resting 

 within a cocoon. 



