246 S. J. JOHNSTON. 



The eggs, which are very thin shelled, increase very 

 considerably in size during their passage along the uterus. 

 In the proximal parts, near the ovary, they measure 0*075 

 x 0*04 mm.; about the middle they vary from 0*081 x 0*043 

 to 0*091x0*053 mm.; and in the distal portion, towards 

 the opening, they attain the size of 0*112 x 0*059 mm. 



This species is closely related to a group of species 

 H. arcuatus, H. Icevigatus, and H. tumidus, all parasitic 

 in various anseriform birds in Europe. Besides a number 

 of minor points, such as the size and shape of the body and 

 the position of the intestine in regard to the sides and 

 posterior end of the body, it differs from all of these in the 

 cirrus sac projecting back much further behind the intes- 

 tinal fork; in the much larger testes, and in having the 

 gonads much closer together; and in having the lateral 

 fields of the yolk glands separated from one another at the 

 posterior end. In the three European species some loops 

 of the uterus pass as far back as the hinder border of the 

 posterior testis or beyond it, while in the Australian form 

 they do not pass further back than the anterior border. 



PART II. 



List of the trematode parasites of Australian birds, 

 together with closely related forms. 



OPISTHORCHIN.E. 



Opisthorchis obsequens, Nicoll, obtained from the liver 



of Hieracidea berigora in Queensland, is related to O. 



interruptus, Brn., found in the South American bird Alcedo 



viridirufa. 



Psilostomin^e. 



Orchipedum sufllavum, Nicoll, parasitic in the oesophagus 

 of the Black Spoonbill Platalea regia, in Australia, seems 

 to find its nearest relative in Orchipedum tracheicola Brn., 

 parasitic in the European Anas fusca. 



