Aiistniliaii Eartlavorms. 249 



slightly developed, and the peritoneal layer is large, and made of 

 very granular cells with large nuclei. At the posterior end, the 

 muscular tissue is more strongly developed, and the peritoneal 

 layer is represented by a thin membrane. I have found no 

 trace of a typhlosole in any of the specimens examined so far. 



Section II. 



Description of Special Features in Species Examined. 



As the structure of the pharynx and buccal cavity appears to 

 be the same in all the specimens examined, except as regards 

 the presence of special nephridia in some forms, as described 

 above, I have not referred to those parts in the following 

 descriptions : — 



1. — Megascolex dopsalis, Fletcher. 



Pepichaeta dorsal is, Fletcher. Proc. Linn. Soc. N.S.W., 

 vol. ii., 1887. 



Plate L., Fig. 10 and Fig. 9. 



(a) Macroscopic. — Buccal cavity and pharynx extend to end 

 of segment 4. Crop in 5. Gizzard in 6. Oesophagus runs 

 from segment 7-16. It is simple in 7 and 16, and dilated into 

 vascular swellings in 8-15. Large intestine commences in 17 

 and is pinched in slightly at each septum. Special bunches of 

 nephridia are situated ventrally at the sides of the pharyngeal 

 region. The description given by Mr. Fletcher differs slightly 

 from this. 



(b) il/icro5co^iV.— Oesophagus in segment 7 has its lining of 

 columnar epithelium drawn up into deep, w*ide folds. There is 

 a large development of circular muscle fibres. Patches of ap- 

 parently glandular tissue surround this part of the oesophagu-i. 

 The structure of the oesophagus in the vascular swellings varies 

 in the different segments. In the first two or three the lining is 

 folded only slightly, and the muscular tissue is reduced very 

 much. In the following swellings the folds increase in length, 

 the muscular tissue becomes strongly developed, and the peri- 

 toneal cells form a deep layer, until in segments 13-15 we get 

 the structure seen in Fig. 8. In the simple portion of the 



