Price is right and that this genus should be made synonymous with p. 350 



Ancyrocephalus, One of the largest differences between these two 

 genera was considered to be the absence of the eyes among Haliotrema , 

 however, this is not correct because among H^ spirophallus Yamaguti, 

 which is at our disposal, there are 4 eyes. It is true that each of 

 them has a very small number of pigmented granules and in addition 

 to that they are relatively clear. Apparently the "glandular cells" of 

 Johnston and Tiegs among H. australe Johnston and Tiegs are also 

 eyes as was also correctly suggested by Price (Price, 1937b). Because 

 of this, this characteristic is discarded and the remaining differences 

 between Haliotrema and Ancyrocephalus can be reduced to details of the 

 sexual apparatus to which one can hardly attribute generic significance. 



Conversely, the species united into the genus Urocleldus must 

 obviously belong not to one but to several genera. Thus, of the 39 species 

 known to us, 3Z have an analogous structure of the copulatory organ in 

 the shape of an elongated pipe fringed by a thin membrane -shaped plate 

 wound around it (Fig. 266). Often this pipe is equipped with a supporting 

 plate, also more or less a conamon type of structure. During the exami- 

 nation of these 32 species, first of all our attention is attracted by the 

 fact that they fall into three natural groups to which different significance 

 has been attached at different times. First, the species among which 

 both pairs of middle hooks are of the same size (genus Urocleidus s. str. ), 

 then species with one pair of middle hooks twice as large as the other pair 

 (genus Haplocleidus auct. ), and finally species in which the middle hooks 

 have a flat outgrowth in the shape of a plate rounded at the end above the 

 edge or point, which serves apparently for pinching part of the gill fila- 

 ment between it and, the point (genus Pterocleidus auct. ). Of the 32 species 

 of these groups mentioned, 26 are encountered only on Centrarchidae, 

 4 on Serranidae, 1--Percidae and l--Catostomidae. The first 3 families 

 of hosts are closely related to each other; i.e. , supplemented by the 

 circumstance that only these three families of the superfamily Percoidae 

 occur in the fresh waters of North America where Urocleidus s_. lat. live. 

 Thus, according to occurrence, only the finding of this species on 

 Catostomidae- -which are far removed from Perciformes, is an exception. 

 This 8pecies--H. moorei Mizelle--was encountered in the number of 4 

 samples Catonotus flabellaris (Raf. ) in the state of Tennessee (U.S.A. ). 

 The description does not give any reason to doubt its belonging to 

 Urocleidus s. str. in spite of the fact that the author writes that certain 

 peculiarities in structure make this species closer to the genus 

 Cleidodiscus (Mizelle, 1940). 



As regards the remaining 7 species pertaining to the genus 

 Urocleidus , they have a completely different structure of the copulatory 

 apparatus which never bears any membrane -shaped bordering plate on 



415 



