40 ILLINOIS BIOLOGICAL MONOGRAPHS [328 



verse cx)il is situated] direkt ventral, um regelmassig abwechselnd links oder 

 rechts neben der Vagina auszumiinden. " 



Sections show that the actual opening is formed by the rupture of the bot- 

 tom of a cup-like invagination of the cuticula from the ventral surface, which 

 meets the end of the duct with a diameter of from 25 to 40/i. As Fuhrmann 

 stated, " Dieser Ausfuhrgang der Uterus ist von der Stelle an, wo er ins Rinden- 

 parench\Tn tritt, wie die Vagina und der Cirrusbeutel, von zahlreichen Paren- 

 chymmuskeln umhullt und von einer der Korpercuticula ahnlichen Membran 

 ausgekleidet;" but the cuticula seems to appear as such only near the opening, 

 since only half-way back along this dorsoventral limb of the organ flattened 

 nuclei are distinctly seen. In other words the flattened epithelium of the 

 uterus, which, showing only a few scattered nuclei, was described by Kiessling 

 as a "fine, structureless but elastic membrane," passes insensibly into the 

 cuticula near the opening, no distinct line of junction between the two being 

 discernible. This latter statement is likewise applicable to the similar struc- 

 ture of the vagina. 



The dimensions of the ellipsoidal eggs in the sections of the uterus were 

 found to be 62 to 65 by i?> to 36^. Kiessling gave them as 49 by 37/i and 

 Fuhrmann as 70 by 29ju. In discussing the latter, however, Liihe (1899a:718) 

 remarked that not only did he find variations from 38 by 22 to 56 by 38ju in 

 the size of the eggs in material of B. zschokkei sent to him by Fuhrmann, but 

 that in general even greater variations than these are to be found in other spe- 

 cies according to the various writers. 



Our knowledge of the life-history of this species dates from the time of 

 Abildgaard (1790) who, as mentioned above, was the first to experiment with 

 the larval individuals found in fishes. Creplin (1829) united the two forms 

 which were considered to be two separate species into one species, evidently 

 on the basis of the previous work, especially Abildgaard's (cf. Donnadieu, 

 1877:340), while Donnadieu in his elaborate experiments on the life history 

 of Ligula unfortunately did not differentiate between it and Schistocephalus. 

 The development of the fertiUzed embryo into the oncosphere was first studied 

 by Willemoes-Suhm (1869) and later more in detail by Schauinsland (1885:555), 

 since when nothing of special importance has been added, so far as the writer 

 is aware. Hence up to the present nothing is known about the development 

 of the oncosphere into the larva in the intermediate host, as is indeed the case 

 with most of the bothriocephalids. 



As regards the identity of the material studied with the European species 

 it will be seen from the above comparisons that, while there are many dis- 

 crepancies among the data given by Kiessling, Fuhrmann and Solowiow, those 

 by the latter departing the farthest in many respects, the resemblances so out- 

 weigh the differences as to make the erection of a new species unjustifiable. 

 The thickness of the cuticula, the diameter of the excretory vessels, the dimen- 

 sions of the seminal vesicle, the ovary and the eggs, which constitute the 

 majority of the differences, might easily be explained by differences in age of 

 the material studied. But the number of testes (100) as given by Fuhrmann 



