Parasitic Worms from East Africa. 293 



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

 there is little external sign o£ segmentation, the inter- 

 segmental divisions being marked only by a slight constric- 

 tion. There is no sign ot" 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. Tlie youngest segments 

 are much broader than long. Mature and early gravid 

 segments are about twice as broad as long^ while posteriorly 

 tlie length gradually increases in proportion to the breadth, 

 the last three or four se^'ments beino- ionoer than broad. 



The genital pores are irregularly alternating, and are situated 

 iieai- the anterior corners of the segments. 



Internal Structure. 



In a transverse section the medullary parencliyme occupies 

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

 longitudinal muscles, tlie itmer layer, which separates the 

 cortical from the medullary parencliyme, 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 parencliyme, 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 

 sejiinents 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 dorssil 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, c'/.) about 0"1 mm. long, with a narrow lumen distal ly-, 

 but expanding into a wider chamber proximally. The genital 

 ducts ])ass between the two excretory vessels, and (assmning 

 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 Oochorisiica in which the 

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

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

 the genital cloaca. It measures about 0*15 X 0'07 mm. The 



