134 THE APODID^ parti 



what to anticipate a description of the genital 

 glands. 



These glands are segmental tubes running dorso- 

 ventrally on each side of the intestine, inside the 

 intestinal blood sinus. They are separated from the 

 intestine only by the incomplete longitudinal dissepi- 

 ments formed by the dorso-ventral muscle bands 

 described above. The genital tubes commence in the 

 first trunk segment, but become gradually shorter and 

 shorter till they are quite rudimentary in the larval 

 segments of the abdomen ; they cease to be deve- 

 loped at all some distance before reaching the last 

 limb-bearing segment. These segmental tubes are 

 branched at each end. At the tips of the branches 

 eggs develop which arc found projecting, not into 

 the tube, but into tJie body cavity^ as will be more 

 minutely described in the next section ; it is, how- 

 ever, important for our argument to mention the fact 

 here. 



All the segmental genital tubes on each side arc 

 connected together by a longitudinal canal which runs 

 through them all, and acts both as oviduct and shell- 

 or rather shell-secreting gland (see Fig. 32), so that 

 eggs coming dorsally and ventrally from the ends of 

 the branches meet in the middle, and then travel 

 along the longitudinal canal to near the middle of 

 its course, where a descending canal leads to the 

 exterior. 



The question is, Can these organs reveal anything 

 about the vanished nephridia ? It is obvious that 

 they are not themselves the nephridia ; they are 



