As regards the cephalic end of Bothitrema, according to the data 

 of MacCallum (MacCallum, 1913a) and of Price- -based on a few specimens 

 which were collected by the first author, it has "head glands scattered in 

 the pre -oral part of the body and has not gathered into lateral groups as 

 among other representatives of the family (Dactylogyridae--B. B. ) which 

 (glands) open outside through 4 pairs of cup-shaped cephalic organs, " 

 (Price, 1937b), On the drawings in the works of both authors the cephalic 

 end is actually represented with such cup-shaped depressions, more distinctly 

 drawn in MacCallum's, and less distinctly in Price's. In our specimens, 

 the structure of the anterior end is somewhat different (see Fig. 19). On p. 397 

 both sides of the cephalic end lie the thickened lobes which have a clearly 

 glandular nature which resembles the one among the younger individuals of 

 Nitzschia and even Benedenia . During the careful study of the lobes on our 

 whole mounts we can see that they undoubtedly also have, in addition to glandular 

 tissue, muscular tissue, apparently forming the depressions which were 

 observed by MacCallum and Price and which are either not expressed at 

 all or are hardly noticeable on some materials. Thus, one can suppose that 

 the cephalic end of Bothitrema has a somewhat different type than the rest 

 of Tetraonchidea and is close to the corresponding part of Monocotylidae 

 and especially of certain Capsalidae. The internal organization of these 

 interesting worms generally is not completely clear and, in this connection, 

 we can hardly add anything to the data of Price. The elongated sac -shaped 

 form of the intestine is important. In a small number of sections made 

 from the middle part of the body of one worm (in the region of the ovary and 

 of the testis) it is apparent that the intestine has two folds, that it is precisely 

 sac -shaped and not pipe-shaped as in Tetraonchidae and Tetraonchoididae and 

 in each trunk of the intestine of Dactylogyridae, Amphibdellatidae and others. 



Thus, the basic traits of the structure of Bothitrema show that the 

 genus cannot be included in the fannily Dactylogyridae as Price supposed and 

 that it belongs to the circle of the order of Tetraonchidea in the first place, 

 and in the second it should be isolated into a special family which is close 

 to Tetraonchoididae, although it resembles the more highly organized 

 groups in a number of characteristics, particularly representatives of 

 Monopisthocotylinea from Dactylogyridea. 



3. Order Gyrodactylidea Bychow^sky 1937 



Monopisthocotylea Odhner, 1912, part. ; Polypisthocotylea 

 Odhner, 1912, part . 



Polyonchoinea having larvae with 16 edge hooks on the attaching 

 disc. The attaching apparatus of the adult fornns consists of a chitinous 

 armature consisting of edge and middle hooks and often equipped with 

 connecting plates. Among highly organized groups in addition to that 

 there are 2 to 6 suckers on the attaching disc. The copulatory organ has 



475 



