1911] Watson: The Genus Gyrocotyle. 421 



covering. The conditions of Gyrocotyle indicate very clearly 

 that the subcuticular layer is related to the cuticular muscula- 

 ture, and that some at least of its cells are to be considered the 

 myoblasts of the cuticular muscles. There is much in the litera- 

 ture of the subject in harmony with this suggestion ; Blochmann 

 (1896) shows in his diagrammatic cross-section of Ligula myo- 

 blasts lying near the subcuticular layer. He was able to distin- 

 guish these cells from the rest of the subcuticular layer. This the 

 writer is unable to do in Gyrocotyle. The fact that the cuticular 

 musculature always increases with the thickness of the cuticula, 

 disappearing as the cuticula thins out and passing into the 

 fibrous nucleated layer above described, lends support to the 

 suggestion. In the lining of the receptaculum seminis and the 

 posterior end of the vagina, no subcuticular cells can be seen. 

 These ducts are surrounded by simple nucleated muscle fibres. 

 In the early coils of the uterus, where this same nucleated 

 fibrous lining is found but where cilia are also present, the cilia 

 pass through the fibrous layer and are in connection with scat- 

 tered nuclei lying just beneath the fibrous lining. Further 

 along the course of the uterus, where a definite non-nucleated 

 fibrous lining has appeared, beneath which lies a cuticular mus- 

 culature, the subcuticular layer appears, just as it does beneath 

 the cuticular musculature of the body-covering. All the facts 

 available indicate that at least a large part of the subcuticular 

 cells are related, not to the cuticula, but to the cuticular muscu- 

 lature as myoblasts. The subcuticular cells in the neighborhood 

 of the spines are probably related to the protractor musculature 

 of these structures. 



II. ORIENTATION. 



The question of antero-posterior orientation of cestodes is 

 one of peculiar difficulty. Their endoparasitic and attached 

 mode of life makes it impossible, in general, to settle the matter 

 by the test ordinarily applied, that of the direction of locomo- 

 tion. The usual custom, reflecting the influence of Leuckart, has 

 been to regard the scolex end as anterior, the free end as pos- 

 terior. Many early workers, among them Perrier, Grassi, and 

 Blanchard, reversed this orientation, looking on the scolex as 



