82 NOTES ON SOMK ENTOZOA. 



are delicate, practically colourless worms -43 mm. in length 

 and -042 mm. in width, which is uniform throughout the 

 greater part of the body. The body bears delicate trans- 

 verse rings. The posterior end tapers rapidly to become 

 pointed, while the anterior extremity narrows more slowly. 

 The whole larva bears a striking likeness to Hahronema 

 muscce. T therefore consider it to be the young form of 

 a Spiroptera sensu lato. 



The species of Spiroptera which infests rats and mice 

 in Australia is S. ohtv.sa. It is thus quite likely that the 

 larvae under review, belong to this species. The probability 

 is suggested V)v the following facts: — *S. obtusa is quite 

 common here. Tts eggs pass to the exterior with the 

 faeces of the rat or mouse and come to reach the earth 

 in the rat holes, or elsewhere where the rat-flea eggs are 

 developing into larva?. The latter are known to be able 

 to ingest rat-cestode eggs with contained embryos, e.g., 

 Hymenolepis diminuta and H. murina which also reach 

 the exterior with the faeces. It is thus not unlikely that 

 the life history of *S'. obtusa is different from that of Hahro- 

 nema muscce, whose eggs become ingested along with organic 

 matter in horse manure by the fly larvae {Musca domestica, 

 Stomoxys calcitrans, and probably other flies). Maturity 

 is reached by the ingestion of the intermediate host V)y 

 the definitive host. As already mentioned, the larva is 

 of the Spiroptera form. Tt occurs fairly frequently, and 

 is known to infest at least two species of rat fleas. 



The objection is, that the parasite occurs chiefly in 



Xenopsylla cJieopis, a flea which lives ordinarily in tropical 



and subtropical regions ; and quite rarely in the common 



flea C. fasciatus Mhich forms such a large percentage of the 



aphanipterous population of murids in temperate and 



subtemperate zones and in the colder periods of the year 



in sub-tropical areas. This objection does not appear 



to me to be a very serious one, as the parasite does not 



seem to have been recognised elsewhere, perhaps because 



unsuspected, perhaps because of the difficulty in seeing it 



unless very little light be allowed to pass through the 



specimen. 



Sfephanurus dentatus, Dies. 



The "■ kidney worm " of pigs was recognised many years 

 ago in Queensland by Morris, in 1871, and by Bancroft 



