of a few Annelids. 24)7 



the base of the curve, as in the adult Poly dor a. The anal ring 

 has taken a somewhat funnel-shaped form, with which the little 

 worms can attach themselves quite firmly ; this anal disk (fig. 34) 

 is made use of by the adult almost as freely as the sucking-disk 

 of a leech. 



In the adult (fig. 33) the dorsal cirri equal in length the 

 thickness of the body, and have lost their vibratile fringe ; the 

 glands have taken a great development, consisting of no less 

 than from thirty to forty comma- shaped bags packed closely 

 together within one envelope, as in fig. 36. The digestive 

 cavity has undergone slight changes ; the oesophagus has re- 

 mained as in previous stages, but we have a short intestine into 

 which the long stomach empties. When seen from above, the 

 head is pointed ; seen in profile, it projects in a quadrangular 

 flap, and shows the rudimentary tentacles formed at the base of 

 the larger ones (fig. 35). The eyes are small, four in number; 

 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 that of 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 Sulhvan's Island, in the harbour 

 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 to, if 

 not identical with, Polydura ciliatum, Clap. [Leucodora ciliatum, 

 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 Pagenstecherf, and referred by them to the closely 



* Beobachtungcn, pi. 7- fig. 5. 



t "Die Entwickelung von <S»io," in Archlv f. Anat. u. Phys. 1858, 

 p. 610, pi. 23. fig. 4. 



18^ 



