The suborder includes Monocotylidae Taschenberg, Loimoidae 

 Bychowsky fam. nov. , Dionchidae Bychowsky fam. nov, , Capsalidae Baird 

 Acanthocotylidae Price, and conditionally, Microbothriidae Price. 



1. Family Monocotylidae Taschenberg, 1879 p. 364 



Monopisthocotylinea, having middle and large sizes in the 

 adult state. The attaching apparatus consists of a sucker-shaped disc 

 divided by muscular septa into separate depressions, and chitinous 

 armature. The latter consists of 14 edge hooks and 2 middle hooks (they 

 are absent among Empruthotrema), and 4 edge hooks are located at the 

 posterior edge of the disc between the middle hooks, whereas the remaining 

 10 lie along the edge of the disc anteriorly from the middle hooks. The 

 anterior end of the body has two cephalic lobes of different form and often 

 a well -developed adoral sucker. There are 4 eyes among adult forms, 

 they are often subject to scattering which is expressed more or less 

 strongly and more rarely they are completely absent (?). The intestinal 

 tract has two branches not forming outgrowths and terminating blindly. 

 The male sex aperture and the aperture of the uterus are located medially. 

 The copulatory apparatus has a chitinous pipe without a supporting chitinous 

 apparatus. There is one testis rounded or divided into three parts, more 

 rarely there are many testes. The ovary is flask-shaped, embracing one 

 of the intestinal branches. The vaginal ducts are always (?) present. They 

 are single or double. 



Parasites of marine Elasmobranchii, and as an exception 

 Holocephali. 



Four subfamilies belong here--Monocotylinae Gamble, Dasy- 

 batotreminae Bychowsky subfam. nov. , Calicotylinae Monticelli and 

 Merizocotylinae Johnston and Tiegs. 



The basic leading characteristic of the family is the structure 

 of the attaching disc and not of the attaching armature as among the preceding 

 groups. The reasons for this are quite clear, because the basic role in 

 the attachment of the animals within the present family is played by the 

 disc itself, whereas the attaching armature is used basically during the 

 early stages of development. Apparently the adult animals hardly use 

 either the edge hooks or the middle ones in spite of the fact that in 

 separate species the latter attain rather large sizes. 



The basic trends of development of the attaching discs of 

 Monocotylidae are fully determined. One must consider the discs of 

 Monocotyle and Heterocotyle as being the most primitive. They have a 

 distinct octoradial symmetry, thanks to the presence of 8 muscular septa 

 leading from the circular muscular ridge which surrounds the central 



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