340 



Memoirs of the Indian Museum. 



[Vol. VII, 



In the female, the vulva is situated at about o*i8 mm. from the anterior end. 

 Its position is usually marked by a sudden change in the diameter of the worm, the 

 portion anterior to it being much narrower than the rest of the body. The general 

 arrangement of the female organs is shown in fig. 70. There is no ovejector or 

 muscular vagina. Only one genital tube is complete and functional. The uterus 

 runs back almost straight for some three-quarters of the length of the body, and 

 shows little accumulations of imperfectly-formed ova here and there along its course. 



Fig. 71. — Scolecophilus lumbricicola. Tail of male; ventral view. 

 a.p., accessory piece; s., left spicule. 



The coils of the oviduct and ovary are confined to about the posterior third of the 

 body. The other uterus appears to be represented by a blind sac, lying alongside of 

 the anterior portion of the functional uterus, and serving as a reservoir in which the 

 fully-formed ova are stored before being laid. This sac may run back, in large 

 specimens, to a point about 25 mm. from the anterior end, and is generally crowded 

 with eggs. These are of oval shape, with a thin shell, measuring about o - o65X0 038 

 mm., and containing a crescentic embryo. 



The absence of one branch of the uterus is not uncommon among nematodes, and is most frequently 

 seen in cases where the vulva has been displaced far from its " primitive" median position towards 

 either of the extremities of the worm. This modification is met with among certain free-living forms, 

 as well as in several families, or isolated genera and species, of nematodes parasitic in vertebrates. But 

 there is one group of forms (all of which are, at least during a certain phase of their existence, parasi- 

 tic in invertebrates), to which the present form is perhaps most closely related. This is the group 

 including Allanlonema, Atradonema , Bradynema and Sphaerularia. These forms are generally placed 

 among the Mermithidae, though it seems doubtful whether such a classification would bear critical 

 examination. They do, at all events, share with Mermis and its close allies, with the present species, 

 and with one or two other isolated genera (Aprocta, Aproctonema) , the peculiarity of having no posterior 

 opening to the intestine in the adult form. The alimentary canal is, moreover, in these forms, either 



