On the Young Stages of a few Annelids. 333 



species of Serine here investigated is probably the JVerine 

 coniocephala of Johnston.* 



Phyllodoce maculata Oersted.^ 



Max Mliller is thus far the only one who has observed larvae 

 of Phyllodoce \$ from his description they must have been in 

 a condition nearly identical with the oldest larvae here repre- 

 sented, Fig. 52. The youngest stages, Figs. 46-47, have a 

 slight resemblance to the larvae of Polynoe, figured by Sars,§ 

 Max Miiller,|| and Claparede.T "We find in these earlier stages 

 a very powerful ring of vibratile cilia extending round the 

 middle of the anterior part of the animal, but no trace of cilia 

 round the anal extremity. There are two very prominent eyes 

 placed near the anterior extremity, and two quite rudimentary 

 tentacles. There is as yet no exterior communication from the 

 digestive cavity, which is simply blocked out, occupying little 

 more than two-thirds of the space in front of the vibratile ring 

 and of the large shield extending behind it ; when seen in pro- 

 file, Fig. 47, upper fig., the cavity is somewhat retort-shaped, 

 and occupies mainly the dorsal portion of the embryo. Imme- 

 diately behind the shield, Fig. 46, we find the small, conical 

 body, where we can already trace the first indications of the 

 broad paddles of Phyllodoce, as delicate transverse swellings 

 on each side, connected by slight articulating lines. The arti- 

 culations are tolerably distinct when seen in profile, Fig. 47, 

 upper fig. ; from this point of view the embryo appears far 



* Mag. Zool. and Bot. 1838. II. PI. II. Figs. 9-13, p. 70. 



+ Oersted A. S. Gronlands Annulata dorsibranchiata. 1843. PI. III. Fig. 

 46, p. 39. 



\ Mullek Max. Note on p. 17 ; in Archiv f. Anat. u. Phys. 1855. 



§ Sars M. Zur Entwickelung der Anneliden ; in Archiv f. Nat. 1846. I. 

 p. 11. PL I. Fig. 12. 



II Muller Max. Ueber dei Entwickelung u. Metamorphose der Polynoen; in 

 Archiv f. Anat. u. Phys. 1851. p. 223. PI. XIII. 



«[[ Claparede A. R. E. Beobachtungen PI. VIII. Figs. *7-8. 



