TREMATODES OF AUSTRALIAN BIRDS. 



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indentations along the margins. The anterior measures 

 0*78 x 0*69 mm., and is almost entirely on the left side of 

 the middle line, the opposite side being occupied by the 

 comparatively large cirrus sac, which lies alongside it. 

 The posterior testis lies with its base anterior and apex 

 posterior, the base being somewhat concave. 



The testes are 0*5 mm. apart, and in the space between 

 them is found the ovary (0*33 x 0*252 mm.), on the right side, 

 oval in shape, and with an entire outline and some coils 

 of the oviduct including the ootype etc. There is a short 

 Laurer's canal opening near the middle line on the dorsal 

 surface, but no receptaculum seminalis. The gland of Mehlis 

 surrounds the ootype. The comparatively conspicuous vasa 

 deferentia become joined to enter at once the coiled vesicula 

 seminalis, which is completely enclosed within the cirrus sac. 

 This leads to a well-marked genital atrium with a con- 

 spicuous opening in the middle line, on a level with the 

 anterior edge of the anterior testis. The terminal part of 

 the duct of the cirrus is lined by a number of chitinous 

 tubercles or blunt spines. 



The oviduct, after making a number of coils in the space 

 between the testes, curves round the left border of the 

 anterior testis and just in front of it opens into the uterine 

 sac. The latter is a conspicuous object even in the whole 

 mount, and reaches forwards as far as the junction between 

 the anterior and middle third of the body. The uterine sac 

 opens into the genital atrium some distance behind the 

 point at which it is joined by the oviduct. Neither the 

 uterine sac nor the oviduct, in either specimen, contained 

 any eggs, so that I infer the specimens were not quite 

 sexually mature, though the vesicula seminalis was filled 

 with sperms. The immaturity of the specimen was also 

 shown by the state of the yolk glands, which had only just 

 begun to make their appearance, and occupied a small field 

 behind and to the right of the gonads. 



