INTRODUCTION. XC1X 



the Polyzoa, is the ciliary wreath or corona (Woodcut, 

 fig. xlii.). 



The other portions of the larval structure are des- 

 tined to pass into the adult organism, the aboral face 

 always constituting the zooecium, and the oral pene- 

 trating into the interior to form the rudiments of the 

 principal internal organs *. 



Claparede had previously criticised the views of Schneider 

 and Nitsche respecting the complete dissolution of the 

 larva, and had maintained that in the case of BuguJa the 

 retrogressive change limits itself to the loss of the cilia 

 and the " whip," or tuft of setifonn appendages f. 



If Barrois's view be correct (as we have every reason 

 to believe), we get rid of the anomaly that would be in- 

 volved in the reduction of the complex larval structure 

 to a mere homogeneous mass. We have to do with an 

 ordinary case of metamorphosis : certain elements of the 

 larval form, it is true, are histolyzed, and give rise to a 

 mass of granular matter ; but this in nowise prevents the 

 passage of the organs of the larva into those of the adult. 



In the case of the Entoprocta, the general opinion 

 has been that the larva passes directly into the perfect 

 animal ; the observations of Van Beneden[J and Uljanin 

 seemed to leave little room for doubt. In the larva of 

 Pedicellina the internal organs are very fully developed, 

 hey exist in the adult; even the rudiments of the re- 

 productive organs and of the brood-chamber are said to be 



Comptes Rendui, 23 Sept. 1878. 



t Zeibch. f. wiuenoch. Zool., Deo. 1870. 



t ' Recherche*,' Ac., Mem. Aead. Boy. Belg. xix. pp. 80-32. 



"Zur Anatom ir u. Entwicklungsgeach. d. Pedicellina," Bull. Soc. Imp- 

 d. Naturalises de Mo*cou, xlii. (1869) p. 435. See al*> Vogt on Loxosoma, 

 ArchireB de ZooL expt'rimentalt'.' 1>77; translated by the author, Quart. 

 Journ. Micr. Sc. (n. .) XTU. p. 366, note. 



