300 CALIFORNIA ACADEMY OF SCIENCES. 



ently backwards and connect with the body-wall in 

 somite vi. 



CEsofhagus (tigs, i, 2, 18 and 19) commences at 

 the posterior end of the paryngeal and buccal region, 

 there being no gizzard. The oesophagus is greatly 

 sacculated, much more so than in any species of Ocnero- 

 drilus, and the expansions in the various somites are 

 peculiarly unequal in size. This unequalness appears 

 very constant and varies but little in the four specimens 

 sectioned or dissected. 



The anterior expansion of the cKsophagus commences 

 in the center of somite iv directly connecting with the 

 pharynx. The part of the oesophagus which is confined 

 to this somite is very small. In somite v the oesophagus 

 widens, nearly always forming a very large sac which is 

 again divided, the anterior part being the highest, pro- 

 jecting dorsally higher than any other part of the 

 resophagus. 



The following part confined to somite vi is very small, 

 both as regards width and height, being slightly lower 

 than the posterior part of the oesophagus in somite \ . In 

 somite vii the oesophagus is greatly enlarged forming there 

 a large inflated sac which is especially developed later- 

 ally. This part of the oesophagus is almost twice the 

 size of any other oesophageal fold. 



It is followed in somite viii by a very small and princi- 

 pally superiorly developed oesophageal fold which varies 

 considerably in size, but which is always very much 

 smaller than the oesophageal sacculation in somite vii. 

 Seen in longitudinal section the sacculations confined 

 respectively to somites ix, x and xi, are of almost equal 

 size, the one in somite ix being slightly the highest. But 

 it is much developed laterally, more so than an^• other 

 part of the oesophagus 



