784 CONTRIBUTION TO AUSTRALASIAN OLIGOCH^ETA, I., 



The pharynx extends from the anterior region of segment ii. r 

 to the posterior portion of segment v. The lumen of the portion 

 lying in segments ii.-iv. is much wider than that in segment v., 

 appearing in sections as squarish in outline. The anterodorsal 

 region of the pharynx shows an extra thickening due to the 

 development, or rather presence, of several layers of cells, the 

 pharynx in general being lined by a single layer of cells This 

 thickening corresponds to the region of the pocket-like continua- 

 tion of the pharyngeal cavity in A. notabilis. The buccal epithe- 

 lium passes into that of the pharynx at the ventral extremity of 

 the brain, which lies in close apposition to the pharynx. The 

 epithelium consists of very tall ciliated cells, with slightly 

 elongate nuclei. The cilia are much shorter than those of the 

 corresponding cells in A. notabilis ; they appear as a hazy 

 unstained layer internal to the epithelium, so as to readily mark 

 off the pharynx from the posterior portions of the alimentary 

 canal. As the pharynx passes towards the oesophagus in segment 

 v., it becomes suddenly much narrowed so that its lumen is 

 reduced in diameter to about that of the oesophagus, or to one- 

 third of that of the anterior portion of the pharynx. 



The oesophagus is a sinuous tube slightly constricted at each 

 septum and extending as far backwards as segment xiii. It lies 

 in the central portion of the coelome as far as segment viii., in 

 which it is forced towards the ventral body-wall and so as to pass 

 beneath the mass of developing spermatozoa in segment xi., rising 

 again to its former central position in the posterior region of 

 segment xiii. 



The intestine, like that of Plagiochceta and Pontoscolex 

 corethrurus, instead of being in the form of a straight tube, con- 

 stricted to form a distinct pouch in each segment, as is the case 

 in A. notabilis and other Oligochseta in general, is arranged in a 

 spiral fashion. Its anterior portion has the form of a large 

 U-shaped mass extending through segments xiv.-xviii. Thence 

 it proceeds as a gradually attenuated spiral tube as far as segment 

 xxxv., behind which it assumes the form of a straight tube 

 showing a slight constriction at each septum. 



