As a rule the intestinal trunks ternninate blindly at the end of the body; as 

 an exception in Pseudocotyle they merge with each other. The sex system 

 has a common exterior opening of the sex atrium into which open the male 

 sex organ and the uterus and sometimes also the opening of the paired 

 vaginae. The male sex system has a single, double, or numerous testes 

 and a copulate ry organ equipped with a well -developed chitinous pipe 

 which sometimes has a chitinous supporting apparatus. The female systenn 

 has a rounded ovary, w^ith well-developed vitellaria and a singular muscular 

 vaginal duct; sometimes there are 2 vaginal ducts opening independently or 

 into the genital atrium. The uterus is relatively short. 



Parasites of the skin of Elasmobranchii. 



Type genus, Microbothrium Olsson, 1869. 



In addition to this, Dermophthirius MacCallum, 1926; Lepto- 

 bothrium Gallien, 1937; Leptocotyle Monticelli, 1904; and Pseudocotyle 

 Beneden and Hesse, 1865, enter into the composition of the family. 



Limited material on adult and young individuals of Leptocotyle 

 minor Monticelli collected from Scyliorhinus canicula (L. ) from Naples 

 (Mediterranean Sea) and from the same host from the Atlantic Ocean near 

 England was at our disposal. The development of the species and also of 

 other Microbothriidae is not known, which does not permit us to make 

 reliable conclusions about the status of the family in this system. During 

 special examination of our material, which was collected from preserved 

 fishes with all possible care, we succeeded in substantiating the correct- 

 ness of all previous researches in connection with the complete absence of 

 chitinous hooks. Altogether the "sucker" of Leptocotyle gives a very strange 

 impression. In spite of its relatively small dimensions the worms are very 

 strongly attached to the skin of the host and it is difficult to remove them 

 even in the preserved state. In the sections through the "sucker"^ it is 



_ - 



At our disposal were two cross sections stained with iron hematoxylin. 

 The worms were fixed on the body of the host in 4 % formalin. 



apparent that it has a relatively weakly developed musculature but contains 

 a relatively large number of some sort of glands the ducts of which approach 

 the inner surface of the cup of the "sucker',' and apparently their secretions 

 form a lining on the basic part of the above-mentioned surface which on the 

 stained sections has the appearance of a black homogeneous plate. During 

 removal of the worm by steam from the skin of host it is apparent that 

 they are attached to the surface of a separate scale and that epibiasis 

 (overgrowth, nobis) of the sucker of the worm by the tissues of the host is 

 not observed. In such a fashion one can consider it certain that the attaching 



462 



