88 Records of the Indian Museum. [Vol. XIX, 



examples, as Cort (1919, p. 295) found also to be the case in Mar- 

 geana calif orniensis. 



The genital organs, with the exception of the coils of the 

 uterus, lie in the anterior half of the bod}^ and are closely grouped 

 around the acetabulum. A pair of testes (fig. i.t) lie, one 

 on each side, at about the level of the acetabulum : the right 

 testis is as a rule situated rather more anteriorl}^ than the left 

 and is at the level of the anterior acetabular margin, whereas the 

 left testis is usually opposite the posterior margin ; but this 

 difference of level appears to depend on the position of the ovary. 

 Liihe in his original description figures the ovarj^ on the right 

 side of the body, and the right testis anterior to the left ; in the 

 majority of specimens examined by me this was the condition 

 found but in a number of cases, roughly about 30 per cent, of 

 those examined, the ovary lies on the left side of the bod}^ and in 

 these cases it is the left testis that is the more anterior. Liihe 

 further describes the teste? as being triangular or oval and he 

 figures the one lying anterior to the ovary as triangular, and the 

 one on the other side of the body as oval, Johnston (191 2, p. 

 336) in his table for the determination of the species of Mesocoe- 

 limn gives ''Testes triangular" as one of the diagnostic features of 

 this species, but in all cases examined by me these organs have 

 a rounded outline, when viewed from above : in transverse sections 

 they are seen to be somewhat flattened dorso-ventrally and so pre- 

 sent an oval appearance. From each testis a delicate narrow 

 vas efferens arises : these ducts pass forwards and median wards 

 and unite together close to the base of the seminal vesicle to form 

 a very short vas deferens (fig. 2 vd.), which pierces the cirrus-sac 

 at its posterior end. The genital pore (genp.) is situated in 

 the middle line of the body about midwa^^ between the two 

 suckers and a little in front of the point of bifurcation of the 

 oesophagus {vide fig. i) : the cirrus-sac (fig. i cir.) is large and 

 thick-walled and extends backwards from the genital orifice to a 

 short distance behind the anterior margin of the acetabulum ; it is 

 usually slightly curved and is deflected towards the right side of 

 the body. Although Liihe makes no mention of this organ in his 

 original description, he figures it quite correctly. The posterior 

 half of the cirrus-sac is occupied b}' a large bi-lobed seminal 

 vesicle (fig. 2 sv.), which in adult examples is full of ripe sper- 

 matozoa : in front of this lies the cirrus, which is long and 

 narrow and is usually coiled up within the sac. The prostate 

 gland appears to be somewhat diffuse ; it extends backwards 

 around the anterior end of the seminal vesicle and forwards around 

 the cirrus nearl}^ as far as the genital orifice. 



The ovary (fig, i ov.) Hes usually on the right side of the body 

 behind and somewhat to the inner side of the right testis at about 

 the level of the posterior border of the acetabulum, though, as 

 I have remarked above, in about 30% of cases it lies on the left 

 side. In this respect Mesocoelium sociale (Liihe) shows a varia- 

 bility that is exactly similar to that found by Johnston in M . mesem- 



