Vol. xxii] ENTOMOLOGICAL NEWS. 469 



tive, and the insects seemed to seek the inguinal region of Heymon's 

 Cricetomys at such times, but when the rat was sleeping or quiet, 

 wandered over all parts of the body, rarely attracting any response 

 from the rat. Heymons agrees with Hansen (1894) in considering 

 that Hemimerus is most nearly related to the Forficulidae earwigs 

 and in this connection it is worth while to mention the discovery, 

 within the last two years, of an earwig, Arixenia esau, found in the 

 breast pouch of a naked bat in Sarawak, described by Dr. K. Jordan 

 in 1909, and exhibited at the Entomological Society of London, 

 Feb. 2, 1910. 



A RAT-FLEA AS THE INTERMEDIATE HOST OF TAPE- WORMS. The dog- 

 flea and the human flea have long been known to serve as hosts of 

 the cysticercoid stage of the tape worm Dipylidium caniiiuin. Dampf 

 recently found a Cysticercoid, supposed to be that of Hymenolepis 

 nana, in the flea, Mesopsylla eucta, from the jerboa, Alactaga jaculus. 

 Nicoll and Minchin have now found two species of Cysticercoids 

 in the body cavity of the rat-flea, Ceratophyllus fasciatus. 



One of these Cysticercoids has been proved to be the larval form 

 of Hymenolepis diiniunta; it "occurred in about four per cent. (8 

 in 207) of all the fleas examined during a period of thirteen months. 

 It was found in the body cavity and usually only one specimen at a 

 time. As many as three, however, had been found in one flea." 

 Feeding experiments to determine the identity of the Cysticercoid 

 were performed on a litter of young rats, separated from their 

 mother, isolated, and kept under observation until it was certain that 

 they were free from tape-worms. After three months, fleas were 

 mashed up with their food, and nineteen days later mature tape-worms 

 (Hymenolepis diminuta) and their ova were found in the intestine 

 of the rats and in the rats' faeces respectively. It is thought that 

 only the oldest and largest flea-larvae are capable of ingesting the 

 tape-worm eggs and that no development of these eggs takes place 

 until the beginning of the pupal stage. 



Of the other Cysticercoid, only one specimen has been found in 

 Ceratophyllus fasciatus. From a microscopic examination and com- 

 parison with the known tape-worms of rats, "the authors were forced 

 to the conclusion that this Cysticercoid must either be referred to 

 ll[yicnolepis] iintrina <>r tu some other as yet undescribed form, the 

 scolex of which was indistinguishable from that of H. ninrina.'' 

 This discovery is of special interest; first, because it has been belir\oi 

 that H. mitrina dispensed altogether with an intermediate host, passing 

 its encysted stage in the walls of the intestine of the rat itself; sec- 

 ond, because some have considered //. mnrina to be identical with H. 

 nana, a dangerous tape-worm of man ; and third, because no inter- 



