4 AtlT. 4. — I. IKE DA : 



centre there is a yellow and radially striated area bearing the 

 opening of the subdermal gland. On the introvert these papillae 

 become smaller and smaller anteriorly, but without undergoing a 

 noticeable change in height (Fig. 26). They show no striated 

 cental area, the entire surface being finely granulated. Neither 

 hook nor spine is present on the introvert. 



The inner surface of the body-wall is remarkably smooth 

 and shiny. The longitudinal muscles in the same are continuous. 

 The retractor muscles are only two in number, forming a ventral 

 pair (Fig. 27, vm). They originate at the beginning of the 

 posterior third of the body proper, close to the nerve-cord {n). 

 In the anterior parts they are fused together into one flat band, 

 running in contact with the long œsophagus {oe) on the ventral 

 side. Along the dorsal side of the latter runs the dorsal vessel, 

 the posterior parts of which are beset with numerous but short 

 contractile villi {cv). The long intestinal convolution {ic) consists 

 of about 20-25 double spirals, closely twisted around the spindle- 

 muscle which posteriorly does not pass out of the spirals for 

 fixation to the body-wall. Only one, but very long, fixing muscle 

 {fm) extends between the posterior end of the œsophagus and a 

 point in the body-wall situated a short distance in front of the 

 origin of the left retractor muscle on the left hand side. The 

 rectal intestine {re) carries at its beginning a small blind sac, 

 the rectal gland (rg). The rectum is fixed to the body-wall 

 by two broad wing-muscles (wm). The segmental organs {so) 

 are of a conspicuous length ; they are free from the body-wall 

 except at the external apertures which are situated a certain 

 distance in front of the anus. They are colored with a deep reddish 

 brown pigment. The anus is indicated on the outside by a 

 prominent papilla. The sexual organs are, as is usually the case, 



