CHROMODORIS ZEBRA HEILPRIN 629 



a slender tube for 1 cm., passes through the nervous collar, and 

 then expands into a thin-walled sac (15 mm. long by 5 mm. in 

 diameter), the crop (iglv.). From the crop it continues, as a 

 slightly broader tube (3 mm. in diameter), to the anterior portion 

 of the liver mass, where it passes directly into the anterior end 

 of the stomach (fig. 2, ga.). Throughout its entire length, the 

 thin walls of the oesophagus bear longitudinal lamellae on their 

 inner surface. 



The stomach 



The stomach is a large thin-walled sac, 30 mm. long by 15 mm. 

 in diameter, lying within the anterior two-thirds of the liver 

 mass. Its walls are slightly lamellated and perforated by innu- 

 merable large openings, the orifices of the evaginations which col- 

 lectively constitute the 'liver' or digestive gland, so that appar- 

 ently the cavity which we call the stomach is merely enclosed in a 

 loose meshwork. Closely applied to the walls of the stomach 

 are the ramifications of the nephridial organ (fig. 2, ren.). 



The intestine 



The intestine (fig. 2. in.) arises from the right side of the stom- 

 ach about two-thirds the length of the stomach from its anterior 

 end. This tube, at first rather narrow, has its greatest diameter 

 (7 mm.) near its emergence from the stomach, and it gradually 

 grows smaller as it nears the anal opening. From the stomach, 

 the intestine passes anteriorly for about 25 mm. to the left side 

 of the anterior end of the liver mass, where it turns abruptly to 

 the right and runs diagonally crosswise and backwards for 10 

 mm.; then it bends again, continuing posteriorly for 40 mm., until 

 it reaches the anal opening within the branchial circle. The walls 

 bear longitudinal lamellae upon the interior, two especially con- 

 spicuous folds lying side by side upon the median ventral surface. 



JOURNAL OF MORPHOLOGY, VOL. 23. NO. 4 



