768 J. H. ASHWORTH. 



ing. There are in each otocyst from four to six foreign 

 bodies (otoliths), all of which ai-e apparently quartz-grains 

 except two ; these are obviously fragments of spicules. The 

 otocysts of the specimen 11"1 mm. long are faintly visible in 

 a stained preparation of the whole animal cleared in thick 

 cedar-wood oil. They are about 40^ by 25 /i in internal 

 diameter (fig. 18). 



The nuchal organ is easily recognisable; its cells are richly 

 ciliated (figs. 18, 21). 



Neither giant-cells nor giant-fibres can be identified in the 

 nerve-cord at this stage. 



Six pairs of nephridia may be traced in sections. The first 

 nephridium is small, and its anterior end runs forward and 

 pierces the third diaphragm. On the sixth nephridium the 

 gonidial vessel has a covering of cells which have large 

 spherical nuclei. This is the gonad, and it may also be dis- 

 tinguished, though not so clearly, on the fourth and fifth 

 nephridia. 



The above-described post-larval stages are evidently not 

 young specimens of A. c 1 a p ar e d i i, as is shown by the presence 

 of otocysts and six pairs of nephridia. They are the young 

 stages of the variety of A. as si mi lis. 



Ehlers (1897, p. 104) has recorded from Uschuaia a similar 

 gill-less specimen about 6'5 mm. long, which bears nineteen 

 chajtigerous segments. This post-larval stage was found 

 among the "roots" of seaweeds (Tangwiirzeln), and had 

 probably recently settled down to its littoral habitat. 



VI. Adult Specimens of Are ni col a from the Fal kland 



Islands. 



When the foregoing account was ready for press I received, 

 through the kindness of Mr. R. Vallentin, of New Quay, 

 Cornwall, five adult specimens of Arenicola from the Falk- 

 land Islands, and have thus been able to confirm some of the 

 observations described in the former part of this paper. 



