MARIONEIyl/A 357 



-conspicuous ampulla is situated nearly opposite the base of the pharynx. 

 The obscure excretory pore is invariably located in the lip-region opposite the 

 row of cephalic setae. The presence of the duct and ampulla usually causes 

 the pharynx as well as the portion of the oesophagus near the head to be a 

 little nearer to the dorsal side of the body than to the ventral. 



Nerve-ring. The nerve-ring is always a rather conspicuous feature. As 

 a distinct collar it surrounds the oesophagus a trifle obliquely and is of me- 

 dium size, and has arranged both in front of it and behind it numerous large 

 nuclei, whose grouping, however, does not appear to be very orderly. 



Female organs. The female sexual organs are invariably double and re- 

 flexed (T). The vulva, though large, is more or less continuous and not 

 very conspicuous. The well-developed vagina leads inward at right angles 

 to the ventral surface about two-fifths of the way across the body, and, 

 though fairly muscular, is not very amply cutinized. 



The two straight uteri are of such a size as to contain two or more eggs 

 at a time, arranged tandem; these latter are thin-shelled, smooth, usually 

 ellipsoidal or somewhat elongated, and are deposited before segmentation 

 begins. The reflexed ovaries are broad, or of medium width, taper more 

 or less, and extend one-half to two-thirds the distance back to the vulva. 

 The ova in them are arranged single file except near the blind end, where 

 they are arranged irregularly. 



Male organs. -The tail of the male is like that of the female except that 

 it is usually shorter and more pronounced in its features, especially in species 

 lacking a spinneret. Tn all the species that have been carefully examined 

 in this respect, namely in the majority of the species, there are two outstretched 

 testes extending in opposite directions, the anterior one ending a neck -length 

 or more behind the cardia, the other near the beginning of the posterior 

 fourth of the body. The two equal spicula are invariably arcuate, and 

 occasionally strongly so. At their widest part they are one-sixth to one- 

 eighth as wide as the corresponding portion of the body. They are from 

 one and one-fourth to two times as long as the anal body diameter, and 

 when viewed in profile their proximal ends appear to lie opposite to or slightly 

 dorsad from the body axis, very rarely ventrad. The proximal ends are 

 almost always very slightly cephalated by expansion, but they are some- 

 times faintly cephalated by constriction or by contraction. They are some- 

 what slender, of rather uniform width, and rather blunt at the free end, 

 where they sometimes terminate in a simple or denticulate crochet. The 

 gubernaculum, placed at right angles to the distal parts in the spicula, though 

 sometimes of uniform width, usually tapers internally to a blunt or acute 

 point, which lies opposite to or dorsad from the body diameter. From 

 this apophysis muscles lead fore and aft to the dorsal body wall. The por- 

 tion of the gubernaculum applied to the spicula is one-sixth to one-eighth 

 as long as these latter. 



Supplementary organs. Invariably two large, ventral, pre-anal supple- 

 mentary organs are present, though in a few species they are more or less 

 vestigial. They are placed in front of the anus in such fashion that the 

 posterior one is about as far in front of the anus as the spinneret is behind 

 it, and the anterior one about as far in front of the posterior as this latter 

 is in front of the anus. There is, however, some variation in the situation 

 of this pair of supplementary organs in the different species. Nearly al- 

 ways the posterior supplement is a little smaller than the anterior, some- 



