located the convex (rounded) pharynx. The intestine is divided, its trunks 

 terminate blindly or unite posteriorly. Intestinal outgrowths are absent. 

 Neither the testes nor the ovary are branched. The vagina is absent. The 

 uterus is very short. The cirrus is in the shape of a simple chitinous pipe 

 enclosed in a sac. The vitelline system is very remarkable because it 

 consists of numerous thin "vitelline pipes" located in two groups, one 

 anterior and the other posterior in relation to the ovary. After merging, 

 the transverse vitelline ducts form a longitudinal medial canal or duct 

 which opens into the ootype. The posterior transverse vitelline duct has 

 an obvious junction with the intestinal trunks, " (Johnston and Tiegs, 1922). 



To the present family belong 2 genera, Protogyrodactylus 

 Johnston and Tiegs, 1922, (type genus) and Trivitellina Johnston and Tiegs, 

 1922. Both genera contain one species each and were discovered only by 

 the authors who described them from the gills of Therapon spp. (Serranidae) 

 from the fresh waters of northeast Australia. 



In spite of what appear at first sight to be rather detailed des- 

 criptions of the representatives of both genera, they are actually very 

 poorly studied. Much of their structure arouses doubt and demands sub- 

 stantiation and redescription. We shall deal with several basic instances. 

 The structure of the attaching armature is not clear. According to the 

 author, the number of edge hooks is 12 among both genera and species; 

 however, the reliability of this seems doubtful to us just as their dis- 

 tribution pictured in the works of Johnston and Tiegs(Johnston and Tiegs, 

 1922, Table IX, 1 and Table X, 6 and 7) which indicate that the hooks are 

 located in the same places as among the majority of the lowest mono- 

 genetic trematodes and that only the 6th pair is absent; it is known that this 

 pair often is of small size and it is possible to think that it was simply 

 not noticed by the authors, especially since errors are known in their work. 



The structure of the middle hooks and of their connecting 

 apparatus is also not altogether clear. Based on the very slipshod des- 

 criptions and figures of the authors, one can suppose that each of the larger 

 pair of the middle hooks is provided with a supplementary plate analogous 

 (homologous?) with the one among the hooks of Ancylodiscoides , whereas 

 the small pair has a divided middle plate similar to the one among Ancylo- 

 discoides strelkowi Akmerow. If this is so, then it becomes clear that we 

 deal here with the usual scheme of structure of the middle hooks and of 

 the attaching apparatus of both forms among the lowest nnonogenetic 

 trennatodes, and that this essentially does not differ in any way from the 

 ones among representatives of a number of families and in particular 

 among Dactylogyridae. 



428 



