coe: nemeeteans of west and northwest coasts. 25 



are often forked distally, the branches extending forward far in front 

 of their point of origin. 



Near its anterior end the main axial caecum often sends off one 

 or two pau's of large lateral pouches, which commonly branch 

 irregularly, the more anterior pair extending forward far in front of 

 the anterior end of the axial caecum itself. It is these anterior, 

 lateral branches which in many species extend as far as the brain 

 lobes (PI. 16, fig. 97). 



Esophageal caecum.— In two species of Amphiporus which are 

 described in this paper {^A. occidentalis and A. rubelhcs) the alimen- 

 tary canal is further complicated by the presence of a very conspic- 

 uous caecal appendage to the esophagus in addition to a highly 

 developed intestinal caecum. In both these species the narrow 

 esophagus passes beneath the ventral brain commissure and divides 

 into two branches (PI. 20, fig. 121), one situated directly dorsal to 

 the other. The dorsal branch passes into the stomach, while the 

 ventral branch enlarges to form a large tubular chamber which may 

 be called the esophageal caecum (PI. 20, fig. 121), for it is lined with 

 the same kind of epithelium as is the esophagus, and ends blindly 

 posteriorly. This esophageal caecum extends posteriorly in the 

 median line nearly to the most anterior sexual glands. 



In one of the specimens of A. occidentalis it was further com- 

 plicated by bending forward in the median line to form a narrow 

 appendix {app. PI. 20, fig. 121), which has a very narrow lumen 

 and highly glandular walls. 



A transverse section of the body in the region of the appendix 

 shows, therefore, sections of four distinct portions of the alimentary 

 canal (PI. 20, fig. 121), viz., the stomach, intestinal caecum, esopha- 

 geal caecum, and appendix. The stomach, esophageal caecum, and 

 appendix all lie in the median line, one directly above the other, 

 while the branches of the intestinal caecum are situated laterally. 



Cardiac caecum. — Still further complications occur in Amj)hi- 

 porxis occideiitalis, for the stomach iiito which the dorsal branch 

 of the esophagus opens, as described above, extends forward 

 above the esophagus as a broad, bulb-like chamber which ends 

 blindly between the posterior ends of the brain lobes. This 

 chamber may be called the cardiac caecum (PI. 20, fig. 121), 

 representing as it does an anterior extension of the stomach. It 

 is possible that it is little more than an extensive anterior fold, 



