330 On the Young Stages of a few Annelids. 



of the larger ones, Fig. 35. The eyes are small, four in num- 

 ber ; the fifth ring has nine stiff bristles in different stages of 

 growth; their number, however, is not limited, as we always 

 find small ones growing even in the oldest specimens. Their 

 use seems to be, as far as I can ascertain, to assist the worm in 

 retreating into its case when disturbed. 



The adult worms are found between high and low water- 

 mark, about half tide ; they abound in places where there is a 

 mixture of sand and mud, building their cases upright, in 

 large colonies, closely crowded together. The younger stages 

 (Figs. 26-28) were always caught in great numbers with the 

 dip-net, the more advanced stages being raised from them in 

 captivity. Their growth is very rapid, as in less than six weeks 

 they pass from the stage of Fig. 28 to Fig. 32. 



The species here described is probably the same as the Poly- 

 dora found by Claparede on the coast of Scotland ; it is not the 

 species called Polydora cornuta by Bosc, which occurs plenti- 

 fully in sand and mud flats on Sullivan's Island in the harbor 

 of Charleston, S. C. The South Carolina species differs from 

 its northern representative by the length of its head, its short 

 antennae, and greater size. Our species seems closely allied if 

 not identical with Polydora eiliatum Clap. (Leucodora cili- 

 atum Johnst. (Kef.) ) 



Nerine Johnst. 



The youngest stages of this species of Nerine (Fig. 39) re- 

 semble young Annelids figured previously by Busch,* and by 

 Leuckart and Pagenstecher,f and referred by them to the closely 

 allied, if not identical, genus Spio. We find in both the large 

 brushes of stiff, serrated, temporary bristles, observed by Cla- 

 parede in his young Leucodorse, which, at the least disturb- 



* Busch W. Beobachtungen. ... PI. VII., Fig 5. 



f Leuckart R. u. Pagknstecher, Al. Die Entwiekelung von Spio; in Arcbiv 

 f. Anat. u. Pliys. 1858. p. 610. Plate XXIIL, Fig. 4. 



