170 
Larvae of Fleas 
species examined Pulex irritans is peculiar in having three pairs instead 
of two on the dorsal plate of abdominal somites 7 and 8, and four pairs 
on the ninth abdominal somite ; Xenopsylla cheopis and Ctenocephalus 
emits are peculiar in having but a single pair on the dorsal plates of 
abdominal somites 1-6. 
In recently moulted larvae the dorsal plates are not readily dis¬ 
tinguished, and Table II proves of little service. In such cases, there¬ 
fore, it is better to count the whole of the large hairs on the several 
somites and refer to Table III. This table, like the preceding, fails to 
distinguish between Ceratophyllus fasciatus, Ceratophyllus gallinae and 
Leptopsylla musculi, and between Xenopsylla cheopis and Ctenocephalus 
earns. 
TABLE II. 
Number of Pairs of large (i.e. posterior) Hairs on the Dorsal Plates of 
the Larvae of the six Species investigated. 
Thoracic 
somites 
1-3 
Abdominal Abdominal 
somites somites 
1—6 7 and 8 
Abdominal 
somite 
9 
Pulex irritans 
2 
2 
3 
4 
Xenopsylla, cheopis 
2 
1 
2 
3 
Ctenocephalus canis 
2 
1 
2 
3 
Ceratophyllus fasciatus 
2 
2 
2 
3 
Ceratophyllus gallinae 
2 
2 
2 
3 
Leptopsylla musculi 
2 
2 
2 
3 
TABLE III. 
Number of Pairs of large (i.e. posterior) 
Hairs 
carried by the 
various 
Somites of the Larvae of the six 
Species investigated. 
Thoracic Abdominal Abdominal 
somites somites somite 
1—3 1—6 7 
Abdominal Abdominal 
somite somite 
8 9 
Pulex irritans 
5 6* 
7* 
7* 8* 
Xenopsylla cheopis 
5 5* 
6* 
6* 7* 
Ctenocephalus canis 
5 5* 
6* 
6* 7 
* 
Ceratophyllus fasciatus .. 
5 6* 
6* 
5 6 
Ceratophyllus gallinae .. 
5 6* 
6* 
5 6 
Leptopsylla musculi 
5 6* 
6* 
5 6 
* On each side of the body the two ventralmost hairs consist of a long and a short one 
arising close together from the same plate. 
For Abdominal Somite 10 see Table IV. 
