94 NEW GYEODACTTLOID TREMATODES PEOM AUSTRALIAN FISHES, 



The ovary lies in the midline, immediately below the testis. It is slightly 

 oval and elongated longitudinally. A vagina is absent. The oviduct leaves the 

 ovary ventrally and travels forward. It has not been observed in whole speci- 

 mens, but is plainly visible in sections. The shell-glands are represented merely 

 by a glandular thickening in the uterus along its whole length. The vitellarium 

 follows the path of the intestine faiily closely. It is very, strongly developed in 

 the posterior region of the worm, where it occupies practically the whole of the 

 body. Transverse yolk-ducts open into the oviduct immediately in front of the 

 ovary. No permanent yolk-reservoir is present. 



The egg is of relatively immense size, forcing the other stnictures in its 

 neighbourhood out of position when it is fully developed (PL xi., fig. 11). The 

 intestine becomes bent to one side and the vas deferens appears to be pulled from 

 its lateral position to lie more centrally, close beside the intestine. Posteriorly 

 the egg beai's a short blunt spine. The egg figTired, which came from a rather 

 small adult, measured .075 mm. in lengih by .035 mm. in breadth. 



Found on the gills of the freshwater jewflsh or catfish, Tandanus twndanus 

 Mitchell, from the Burnett River, South Queensland. 



Anchylodiscus sp. 



A worm belonging to this genus was found in very small numbers on the 

 gills of a closely allied catfish, Neosilurus liyrtlii, from the Paroo River, South- 

 west Queensland. No detailed study of its anatomy was possible. 



6. Anoyrocephalus Creplin, 1839. 



(Syn. Diplectanim Diesing, 1858, and other authors; Tetraonclnis Diesing, 1858, 

 in part.) 



More or less elongated Tetraoncliinae, in which the disc is not very sharply 

 marked off from the body. Supporting eliitinous armature of the disc present 

 or absent. Minor hooks varying greatly in number; occasionally absent, never 

 mofe than fourteen. Eyes present. Intestine bifurcated, the limbs devoid of 

 caeca and not joining behind. Position of testis and ovary at times in the 

 middle, or in anterior region, or well within the posterior half of body. Testis 

 usually simple but occasionally slightly lobed. Penis simple; accessory copu- 

 latory structures at times jsresent. Vagina always present. Vitelline system 

 extending on either side as a continuous gland from the pharynx to the region 

 immediately behind the teiinination of the intestine. 



From the gills of marine and freshwater fishes. Known, as yet, only from 

 Europe and North America. 



Type species, A. paradoxus Creplin, 1839. 



In 1857 Wagener placed a number of new species in the genus BactylogyruSf 

 a procedure which has led to considerable confusion in the nomenclature of this 

 gi-oup. One species, D. aequans Wagener, 1857, was made, in the following 

 year, the type of a new genus Diplectanum by Diesing, who also placed Dacty- 

 lo gyrus pedatus Wagener in this genus. Wagener, at the same time (1857), 

 described under the name Dactylogyrus unguiculatus, a wonn which proved to 

 be identical with A. paradoxus Creplin, and added another species, Dactylogyrus 

 monenteron. Diesing, in 1858, placed these two foi-ms, as well as Gyrodactylus 

 cruciatus Wedl., in a new genus, Tetraonchus, failing to recognise the identity of 

 T. unguAcidatus with Creplin's original species (A. paradoxus). It was not till 

 1889 that" Monticelli showed these two forms to be the same. The name was 



