572 PRANK E. BEDDARD. 



the cocoon; in the New Zealand Acanthodrilus multiporus, 

 whose development I propose to treat of in another paper, not 

 only the gonads but the funnels of the sperm ducts and ovi- 

 ducts are fully recognisable in advanced embryos extracted 

 from the cocoon. 



I could not findany trace of the gonads in the young Libyo- 

 drilus. This may not be enough to prove that they are not 

 present in the stage which I examined ; but it seems unlikely 

 that they would have been overlooked had they reached any- 

 thing like the development that these organs have reached in 

 the corresponding stages of Lumbricus and Acanthodrilus. 

 The gonads being absent, or at most very slightly developed, 

 it is not surprising that there is no trace whatever to be found 

 of this duct or of the terminal apparatus with which the ducts 

 are connected. All these structures then appear to be later 

 developments than in Acanthodrilus or Lumbricus. 



One of the most striking features in sections of the embryos 

 of Acanthodrilus is the enormous quantity of perivisceral 

 corpuscles present; they are so numerous as to occupy the 

 greater part of the coelom. The amount of the perivisceral 

 corpuscles in Libyodrilus is not at all large. M. d'Udekem 

 (12, p. 31) has commented upon the great abundance of peri- 

 visceral corpuscles in the young Tub if ex just escaped from the 

 cocoon. 



The immature condition of this stage was also shown by the 

 minute structure of the alimentary canal and by its contents. 

 I thought it possible that I might detect some trace of the 

 pouches connected with the oesophagus, which are so important 

 and characteristic a feature of most Eudrilidse ; but there was 

 not the remotest trace visible; the three gizzards were just 

 commencing to be formed, but they had not acquired anything 

 like the proportions which they ultimately assume. In describ- 

 ing the structure of these organs in' the adult worm I have 

 mentioned that they lie in three consecutive segments, and are 

 separated from each other by a short, soft-walled segment of 

 gut. These tracts (cf. fig. 1) are of very much less extent 

 longitudinally than the gizzards themselves; in the youngest 



