ri9(> 



DI!. V. E. BEUDARD ON 



are alternate, though many open successively on to one side. 

 All the pores that I found were on the same side of the body. 



The cirrus-sac is comparatively short *, as in many species of 

 Davainea, but not in all. It only just reaches the nerve-cord. 

 It opens into the cloaca genitalis in front of and to one side of 

 the vagina. The exact shape of the cirrus-sac has been carefully 

 described in many Oestodes by many writers, and thus specific 

 distinctions have been partly based upon its characters. The 

 cirrus-sac of the present species shows that care must be taken 

 in such descriptions. For I find considerable differences between 

 the cirrus- sac in different segments, a state of affairs to be 

 accounted for no doubt by varying contraction of its muscular 

 walls. 



Text-figure 4. 



n . 



f 



h \ 



\ v,d. 



Longitudinal sectioji through cirrus-sac (f.). 

 n. Nerve-cord. o. Orifice of genital cloaca, v. Vagina, v.d. Vas deferens. 



More usually perhaps the cirrus-sac has the appearance repre- 

 sented in text-figure 4, which is drawn from a horizontal 

 section through a more anterior segment. The cirrus-sac opens 

 directly into the cloaca genitalis, and is of the same character 

 and of pretty well the same diameter throughout. The walls are 

 muscular but not thick ; nor are they thicker in one region than 

 in another. The vas deferens jDerforates the muscular coat at the 

 extremity of the sac fairly exactly in the middle line, and is 



* In extended proglottids the cirrus-sac lies obliquely, being directed forwards. 



