Nos. IAND2.] COTYLASPIS INSIGNIS. 33 



The " tuba " resembling that found in Aspidogaster, is a very 

 peculiar modification of the portion of the oviduct next the ovary, 

 resulting in the production of a series of connected chambers pos- 

 sibly used in lodging the egg during the processes of maturation 

 and fertilization. It consists (Fig. 51) of a somewhat dense wall 

 infolded at intervals transversely to form a sort of diaphragm open 

 in the center. This denser part is covered with a cellular portion, 

 the nuclei of whose cells are readily seen. There are no cilia in the 

 " tuba " ; they are readily seen in the adjoining oviduct. I have 

 never succeeded in seeing ova or spermatozoa in these parts, 

 though it is probably here that fertilization takes place. I have 

 found fully formed eggs, composed of egg-cell, yolk cells and shell, 

 in uterus just beyond the yolk-duct, and these must have been 

 recently formed. As I have not paid special attention to this point 

 it is possible that I may yet oe able to get some points in the his- 

 tory of the formation and fertilization of the tgg. I have not suc- 

 ceeded in recognizing any muscular tissue in the walls of the tuba 

 even in sections in which the muscular fibers were particularly dis- 

 tinct elsewhere. 



The oviduct (Fig. 3) beyond the " tuba " runs first posteriorly, 

 where it receives the duct from the yolk receptacle, then trans- 

 versely to the left side beneath the intestine, then with a winding 

 course forward remaining mostly or wholly on the left side. It 

 runs obliquely dorsally through the diaphragm and then runs to 

 the genital pore, where it opens to the exterior. The part of the 

 oviduct next the tuba for a short distance is ciliated, but the 

 remainder of the passage is not. It is lined everywhere with 

 nucleated cells which are clear, tall and strongly nucleated where 

 the tube is not cilated, but in the dilated portions which contain 

 the eggs the wall is of greatly flattened cells whose nuclei are 

 elongate. In the beginning of the uterus muscle fibers do not 

 appear to be numerous if they are present at all, but in most of 

 the passage they are very evident and in two distinct sets trans- 

 verse and longitudinal. The passage is slightly longer than the 

 body, and hence is somewhat coiled, but this is not carried to the 

 great degree that is found in some of the trematodes. It ends at 

 the genital opening where it always comes in from the left 

 opposite to the position of the cirrus sack. In this terminal por- 



