APHANIPTERA, 23 
Between the twelfth and fourteenth days the larvae may spin them- 
selves a small silken cocoon, which lies in and is covered by the 
dust. Not all spin this silken cocoon ; some pupiate into naked, 
immobile nymphs, which gradually assume a darker colour, and 
approach the appearance of the imago. About the seventeenth day 
of pupal life the imago emerges, and very soon commences its rapid 
hopping movements and voracious habits. 
All the larvze do not pupiate at the same time. Some live through 
the winter and hatch in the spring. 
a im 
; ye i if 
oF 
Fic, 2.—-Pupa of Pulex irritans (greatly enlarged). 
Classification. 
Verrall, in his list of British Diptera, 1888, includes the “fleas ” 
in the Nematocera, and thus does away with the old sub-order, 
Aphaniptera. The family Pwudicide is divided into three genera, and 
numbers thirteen species in all, viz. : 
Fam. Pulicide. 
Genus 1. Pulex, L. 
Irritans, L. 
Fasciatus, Bosc. 
Gallinee, Bouché. 
Melis, WIk. 
Sciurorum, Bouché. 
Canis, Duges. 
Erinacei, Bouché. 
Goniocephalus, Tasch. 
Genus 2. ystrichopsylla, Tasch. 
Obtusiceps, Rits. 
Genus 3. Zyphlopsylla, Tasch 
Octactenus, Kolen. 
Hexactenus, Kolen. 
Musculi, Dugés. 
Gracilis, Tasch. 
