1894.] 229 



The chigoe is the only known flea which becomes enclosed in the 

 integuments of its host ; another species (*S^. gallinacea, Westw.), and 

 those of the allied genera Rhynchopsylla, Hall., and Vermipsylla, 

 Schimk., are ecto-parasites, and hang like ticks on the skin of birds or 

 of cattle {yermi2ysylla) . 



The recorded distribution of the chigoe extends over Tropical 

 America and the Antilles, from 30° N. to 30° S., and in late years it 

 has been exported in ballast to Africa, and has established itself in 

 Angola, Loango and the Congo. 



No Asiatic locality has been recorded for it, but it, or a closely- 

 allied species, inhabits China. 



I have recently examined specimens of the ears of sewer-rats, 

 forwarded from Ning-po by Mr. Szigetvary, of H.I M. Maritime 

 Customs, to the Secretary of the Entomological Society of London. 

 These ears exhibit one or more large oval cysts on the margins of the 

 pinna, near its root, which communicate with the exterior by a small 

 circular hole, usually on the border of the pinna, and blocked by the 

 hinder end of the parasite. 



The latter are ovoid in form, tough-skinned, and contracted pos- 

 teriorly into a short, tail-like process which exhibits chitinized 

 structures at the tip. The largest specimen (preserved in alcohol) 

 measures 8"5 mm. in its long axis, and about 6 mm. in breadth. The 

 anterior extremity is produced into four rounded lobes, which almost 

 conceal the minute head, thorax and limbs of the insect, which, owing 

 to their small size, remaiiied undetected for some time. Till they 

 were discovered, the identity of the parasite, which is even less like 

 a normal insect than is a queen Termite, remained unsuspected. 



It is a true chigoe, but not certainly identical with the American 

 species. The shape of the dilated abdomen differs from that shown in 

 published drawings of S. penetrans, and the disparity in size between 

 it and the remainder of the body appears to be somewhat greater. 

 No important differences can be made out between the prse-abdominal 

 region, when mounted in balsam, and the same region in S. penetrans, 

 and the size of the appendages, measured under the microscope, 

 though smaller, does not vary from the size of the same structures 

 shewn in Karsten's drawings more than may be expected between in- 

 dividuals. The common flea is well known to be very variable in size. 



It is to be hoped that Mr. Szigetvary will obtain more material, 

 so that the species can be accurately determined, and its identity 

 established. 



