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A SYNOPSIS OF THE FLEAS FOUND ON MUS XORWEGICUS 

 DECUMANUS, MUS RATTUS ALEXANDRINUS AND 

 MUS MUSCULUS. 



By the Hon. N. CHAELES EOTHSCHILD. 



The three species of the genus Mas mentioned above follow in the wake of 

 civilised man and may be looked upon as more or less domestic animals. 

 Moreover, when they appear in any new locality, they seem to possess the 

 power of eliminating the previously established native species of rats and 

 mice, and they thus obtain for themselves a wider field and the opportunity 

 for a rapid permanent increase in number of individuals. Of the three, 

 Mus rattus alone habitually infests ships, but by accidental transference in 

 vessels from port to port all three have become distributed throughout the 

 world. Australia is especially rich in peculiar local species of rats, abun- 

 dantly distinct from, but to some extent resembling, Mus rattus. This 

 circumstance renders it not improbable that on occasion animals from 

 Australia may have been incorrectly identified with that cosmopolitan 

 species. 



In connection with the spread of plague the three species under con- 

 sideration are of prime importance^ and not less important are the fleas 

 which are parasitic on them. The object of the present paper is to assist 

 students and others towards the rapid identification of the fleas usually found 

 on the common rats and mice. 



Family I. Chigoes (Sarcopsyllid.e). — The rostrum (= labium + labial 

 palpi) consists of three, or fewer, very feebly chitinized segments. The 

 genal edge of the head is in all cases produced downwards into a triangular 

 lobe situated behind the mouth-parts (fig. 1). There are no combs. The 

 three segments of the thorax are always shorter than the first abdominal 

 tergite. 



The Sarcopsyllid^ are not in any w^qy confined to one host and therefore 

 many of the species may occur on rats. They usually attack the head and 

 oars, and more rarely the feet. 



Key to the Genera. 



a. Hind coxa without a patch of spines on the inside. 



a}. Hind femur simple ] . Dermatophilus. 



b\ Hind femur with a large tootli-like projection near the base . . 2, Ilectojysylla. 



h. Hind coxa with a patch of short spines on the inside (tig. 2) 3. Echidnophaya. 



BULL. EXT. RKS. VOL. 1. PART 11. JULY I9IO. K 



