ECHINORHYNCHUS POMATOSTOMI, N.SP. 113 



the three localities birds of the genus Pomatostomus were 

 infested. Several hundred birds have been examined by us 

 from various parts of Australia, but the parasites have not 

 been detected in any of these save in those above mentioned. 

 It therefore seems highly probable that the ordinary host 

 for the larvae consists of birds of the genus Pomato- 

 stomus, and that these have been the dispersing agents 

 throughout Australia, but that occasionally other small 

 birds such as Clhnacteris, Hylaeola, and Aphelocephala r 

 living in the neighbourhood of Pomatostomi can also 

 harbour the larvae. It may be presumed however that the 

 infestation of these other birds is more or less accidental, 

 and that from their habits or the nature of their food, they 

 do not so readily acquire the ova as does Pomatostomus. 

 If many species of Australian birds acted as the ordinary 

 host of the larvae we would have expected to find more 

 instances of invasion in other species, and also cases of 

 birds being infected in neighbourhoods where Pomatostomus 

 was not present. It will be interesting to see whether 

 species closely allied to this genus can also act as distri- 

 buting agents. If any such birds are found to act in this 

 way it would support their position as relatives of the genus 

 Pomatostomus. It is possible that the adult worm may be 

 an inhabitant of the intestine of some birds of prey, and 

 that in this way the life cycle is completed. 



The parasites usually resemble small maggots, about 

 3*33 mm. long, with a maximum breadth of about 1*26 mm. r 

 the surface of the body being transversely wrinkled. The 

 posterior end is bluntly rounded, the anterior extremity 

 being truncate and rather wider. Retracted within the 

 latter lies the rostellum. The lemnisci are nearly 1*25 mm. 

 in length. No other internal structures are recognisable. 

 In one specimen (taken from P. super ciliosus) the rostellum 

 is everted, the worm being fully twice as long as the form 



H- July 5, 1911. 



