the body. It is possible that sometimes one pair of middle hooks (and the 

 edge ?) hooks completely fall off. The clannps are of a type similar to 

 the discocotylid but differ by the presence of a number of supplementary 

 chitinous structures. In the first place they have 2 transversal rod-shaped 

 plates lying between the lateral parentheses of the posterior valve of the 

 clamp. The vaginal duct apparently is always single and opens by a dorsal 

 pore. The remaining characteristics are similar to the ones of 

 Microcotylidae. 



Parasites of marine Perciformes, predominantly Carangidae, 

 Scpmbridae and other close families. One genus is known from Mugili- 

 formes. 



Type genus, Gastrocotyle Beneden and Hesse, 1863 



Into the composition of the family also enter AUopseudaxine, 

 Yamaguti, 1943, Pseudaxine Parona and Perugia, 1890, Pseudomicro- 

 cotyle Sandars, 1947, Pricea Chauhan, 1945, Lithidocotyle Sproston, 1946, 

 Chauhanea Ramalingham, 1947, and Thoracocotyle MacCallum, 1913. 



The structure of the clamps, complicated in comparison with 

 Microcotyle, is characteristic for the family and this complication bears 

 a progressive character and leads to the formation of almost a continuous 

 surface of chitinous lining, particularly in the posterior valve, similar to 

 the one which occurs in Mazocraeidae. The clamps of Gastrocotyle, 

 Pseudaxine , AUopseudaxine , Chauhanea and Thoracocotyle are fully 

 symmetrical whereas in Pricea, Pseudomicrocotyle and Lithidocotyle they 

 acquire a sharply expressed asymmetry and because of this the right and 

 left rows of clamps are mirrored. As regards the disc itself, it also has 

 a tendency towards sharp asymmetry. Thus, typical genera of the family, 

 Gastrocotyle , Pseudaxine, and AUopseudaxine, have a disc with one row 

 of clamps. With this in the first genus it represents so to speak the edge 



of the body on which lies a series of clamps extending anteriorly con- 



D 446 

 siderably further than the ovary, whereas in the second and third it is ^' 



delimited just as takes place in Axine. Undoubtedly there is a tendency 



toward asymnaetry in Thoracocotyle whereas the 4 remaining genera have 



more or less symmetrical discs. 



The location of the middle hooks In some genera Is curious. If in Gastrocotyle, 

 Pseudaxine, and Thoracotyle 2 pairs of middle hooks lie in the posterior end of the body (on 

 the other hand, nobi s), the posterior end bears only one pair In Lithidocotyl e, Pseudomicro - 

 cotyle and Pricea. ^ It Is remarkable that In the last genus there Is 



^ What happens In AUopseudaxine and Chauhanea is not clear. 



534 



