64 CALIFORNIA ACADEMY OF SCIENCES. 



this region. The index lines 5/. are directed to the hp on 

 opposite sides of the orifice. The figure also shows that 

 the lumen of the duodenum becomes considerably ex- 

 panded immediately behind its junction with the stomach. 

 But it is at the entrance of the duodenum into the chylific 

 vesicle that the most pronounced valve occurs. This is 

 shown in part in fig. 9, pi. i, but much better in the series 

 of figs. 23, 24, 25 and 26, pi. iii, taken in serial order from 

 the duodenum toward the chylific vesicle; /. d. in each 

 section indicating the lumen of the duodenum. It will 

 be seen that in 25 the lumicn has become much narrowed, 

 while in 26, where the coeca of the chylific vesicle be- 

 come confluent with it, it is almost closed. These four 

 sections also show well the relations of the coeca. The 

 section shown in fig. 25 is three sections — about 40 /' — 

 farther back than that shown in fig. 24; and the one 

 shown in 26 is two sections — about 24 // — back of the one 

 shown in 25. It is thus seen that they are not deep. Fig. 

 26 is taken from the region where they all become con- 

 fluent with the chylific vesicle, just at the entrance of the 

 duodenum into this latter. 



I should call attention to the deep pits in the inner sur- 

 face of the wall of the duodenum. These are shown in 

 figs. 23 and 24 o\ ctv. They are in many cases quite 

 deep, and make the wall less than half its normal thick- 

 ness at their bottoms; and frequently the wall bulges out 

 somewhat v/here the pit is situated. What the significance 

 of these may be I am not certain, though it seems prob- 

 able that they are for the purpose of increasing the inner 

 surface of this portion of the tract. Although the figures 

 do not show this to be the case, it is nevertheless true that 

 the perforated cuticulum, which will be described as be- 

 ing present on the inner surface of the wall of the duo- 

 denum, extends dowm into these pits. This would appear 



