646 F. F. LAIDLAW. 



or short tube, which is blocked up by a small chitinous plug 

 {Ch. A.). Tliis latter agrees with the " Chitinanliang " de- 

 scribed by von Graff for Hyporliynchus coronatus, v. G. 

 [2], and with a similar organ found in many other forms. 



Owing to the way in which the walls of the bursa seminalis 

 merge into the parenchyma in whole preparations it is only 

 possible to determine the position of the Inmen. In sections 

 some distinction, as pointed out above, can be drawn between 

 the tissue immediately surrounding the lumen and the 

 parenchyma proper. In no case that I have examined does 

 the bursa seminalis contain spermatozoa. 



I have found considerable difficulty in interpreting the 

 funnel-shaped organ which I have called the receptaculum 

 seminis; the explanation here put forward of this organ was 

 suggested to me by an examination of a figure of Byrso- 

 phlebs Graff ii (Jens.) in Jensen's work ' Turbellarier ved 

 Norges Yestkyst ' [1]. 



In Byrsophlebs Graffii the riper end of the single 

 ovary is posterior, and immediately behind it lies an organ 

 which Jensen calls the receptaculum seminis. This recepta- 

 culum opens to the exterior, and contains spermatozoa which 

 do not, however, according to Jensen in his account of this 

 species, reach it directly, but pass through the opening into a 

 bursa copulatrix (the receptaculum and bursa having a 

 common opening), and from the bursa travel along a long 

 convoluted duct, called by him the ductus longus, into a 

 receptaculum. Now it is evident that, so far as its position 

 goes, the receptaculum bears the same relation to the ovary of 

 Byrsophlebs Graffii, as does the funnel-shaped organ to 

 the ovary of Typhlorhynchus nanus. Both, moreover, 

 contain spermatozoa. 



The organ called by Jensen bursa copulatrix would, then, 

 be homologous with the organ which I here call the bursa 

 seminalis. My reason for adhering to the latter name is that 

 it is used by von Graff to designate a comparable organ in 

 Hyporhynchus and other genera. 



If, then, we may suppose that the receptaculum seminis in 



