expressed in the fact that Price not only changed the name but showed more 

 or less correctly its scope^ which sharply differs from that of Octocotylidae 

 in the understanding of Monticelli, (Monticelli, 1903). 



clamps in the adult (Fig. Z97) is characteristic. The latter were described 

 sufficiently in detail in our common work with L,. F. Nagibina (Bychowsky 

 and Nagibina, 1954). Basically one must say that in spite of the considerable 

 difficulties in the examinations of clamps in this group, which are further 

 complicated by the different condition of the clamp in preparations and by 

 different correlations of the separate parts depending upon the degree of 

 opening for all genera, the presence of 5 mutually articulated parts forming 

 a one-piece capsule, which opens only from one side, representing the 

 opening of the clamp by means of the edges of which the pinching of the 

 tissues of the gills of the host takes place, appears as characteristic for 

 the family. 



This capsule as a whole apparently corresponds to a much 

 thickened and developed subcuticular membrane of other Oligonchoinea; how- 

 ever, it is not possible to say this with full certainty because the develop- 

 ment of clamps of this type has not been studied. Likewise it is not possible 

 to state whether altered edge hooks, in the places of which the clamps are 

 incepted enter into its composition. As regards the separate parts of the 

 clamp of Mazocraeidae, they are always strictly determined although they 

 have different sizes and shapes among separate species and genera. Two 

 plates form the basis of the clamps. The first (Fig. 297, A) has strongly 

 serrated edges and is characterized by the presence of two rows of openings 

 at its central part, apparently serving for the passage of several clusters 

 of musculature. The second plate (Fig. 297, B) is more rounded, it 

 adjoins the first or is partially superimposed upon it, at the same time the first one 

 forms the lower part of the anterior valve and the second, the corresponding 

 (part, nobis) of the posterior. The edges in the upper parts of the valves 

 form two wide "lips" (Fig. 297, C, D), of which the first has larger 

 dimensions and its ends are bent inside the clamps serving as its "springs. " 

 Apparently the last, the fifth part (Fig. 297, E) which has a horse-shoe 

 shape fulfills the same functions. It is located in the posterior valve of 



the clamp. It is tempting to homologize the anterior "lip" of the clamp of 

 Mazocraeidae with the parentheses of Chimaericolidae.both merging with 

 each other at the anterior ends of the edge; however, it is possible that 

 here occurs only a superficial similarity because of the identical function 

 of both formations. The separate parts which were described are connected 

 with each other in such a way that they practically form a single system 

 devoid of large transparent areas and having a cup-shaped form. The 

 opening of this cup is elongated in the transversal direction and its opening 

 can be very large, although basically we almost never observe it as full. p. 419 



As a rule the motion of both "lips" takes place within an angle of not more 

 than 60 to 70 degrees. The described structure of the clamps is encountered 



501 



