On an Ausimlian Land Nemertine. 93 



Professor von Gratf.* The month, us ahead}' observed, is 

 situate just in front of the cerebral ganglia, within the 

 rhynchodcieum (Fig. 6, m.) The alimentary canal, as 

 observed by von Graff, is divisible into two sections, the 

 oesophagns and the gnt proper, which differ essentially in 

 the character of their lining epithelium. The oesophagus 

 (Fig. G, «s.) is at first a very narrow and short tube, 

 with thin walls (pes. ]), which pa.sses obliquely backwards 

 and downwards beneath the ventral commissure of the 

 cerebral ganglia. Behind the ganglia it suddenly dilates 

 into a large saccular structure with thick and folded walls 

 {oes. 2), lying beneath the most anterior portion of the 

 proboscis sheath ; then it contracts again to form a straight, 

 short, thin-walled tube {oes. 3) springing from the posterior 

 dorsal region of the saccular portion. At its posterior 

 extremity the straight, thin-walled tube joins the gut 

 proper. The relations of the different regions of the 

 oesophagus to one another and to the other organs of the 

 body will be best understood by reference to Figure 6, 

 representing a median longitudinal section through the 

 anterior extremity of the body. 



The wall of the oesophagus is made up of more or lesf; 

 elongated, darkly staining, nucleated and richly ciliated 

 columnar cells, and the transition from this epithelium to 

 that of the gut proper is a very sudden one (Fig. 6). Von 

 Graff considers the thick walls of the saccular portion of the 

 oesophagus to be of a glandulai- natm-e ; this may also be the 

 case in our species, but the columnar cells composing them 

 are certainly very richly ciliated. 



The gut proper, or intestine, runs straight from the 

 oesophagus to tlie anus, which is situated at the posterior 

 extremity of the body (Fig. 12, ((.) The median portion 

 of the gut lies exactly beneath the proboscis sheath, but 

 it gives rise on either side to a large number of irregular, 

 often branched, .saccular or lobate diverticula, which pass 

 outwards and upwards on either side of the proboscis sheath, 

 closely embracing it (Fig. 8). 



Just where it joins the oesophagus the gut gives off, as 

 usual, a characteristic diverticulum (Fig. G, d. (jut), which 

 runs forward beneath the last portion of the oesophagus and 

 ends blindly. 



* Lcc. cit. 



