Parasitic Worms from East Africa. 293 



The cuticle is less wrinkled than is usual in the genus, and 

 there is little external sign of segmentation, the inter- 

 segmental divisions being marked only by a slight constric- 

 tion. There is no sign of segmentation at all for about 

 2*5 mm. from the anterior end. This unsegmented " neck " 

 measures 0'9 mm. across at the narrowest part. Behind this 

 about one hundred segments can be counted, but the more 

 anterior of them are very ill-defined. The youngest segments 

 are much broader than long. Mature and early gravid 

 segments are about twice as broad as long, while posteriorly 

 the length gradually increases in proportion to the breadth, 

 the last three or four segments being longer than broad. 



The genital pores are irregularly alternating, and are situated 

 near the anterior corners of the segments. 



Internal Structure. 



Tn a transverse section the medullary parenchyme occupies 

 about one-third of the total dorso-ventral diameter. Of the 

 longitudinal muscles, the inner layer, which separates the 

 cortical from the medullary parenchyme, is the most highly 

 developed, consisting of twenty to thirty bundles of fibres 

 dorsally and a similar number ventrally. Externally to this, 

 in the thickness of the cortical parenchyme, there is another 

 layer, consisting chiefly of single fibres, vaguely subdivided 

 into two concentric series. 



The excretory system, as far as can be seen in the sections, 

 consists of the usual two pairs of longitudinal vessels, which 

 are situated at some distance from the lateral borders of the 

 segments and nearer to the middle line than the longitudinal 

 nerves. Both vessels on either side follow a very tortuous 

 course. One of them is wider and thinner-walled than the 

 other, but it is difficult to decide which is dorsal and which 

 ventral. Transverse intersegmental vessels cannot be made 

 out with any certainty, nor does there appear to be any 

 network. 



Genital Organs. — The genital pore leads into a cloaca 

 (fig. 9, cl.) about OT mm. long, with a narrow lumen distally, 

 but expanding into a wider chamber pioximally. The genital 

 ducts pass between the two excretory vessels, and (assuming 

 that the wider of these is, as usual, the ventral one) ventrally 

 to the longitudinal nerve. (This is contrary to the arrange- 

 ment found in other species of Oochoris/ica in which the 

 point has been studied.) The cirrus-sac (fig. 9, c.s.) is 

 of an elongate pear-shape, the widest part being nearest to 

 the genital cloaca. It measures about 0T5 X 0'07 mm. The 



