INTESTINAL RESPIRATION IN ANNELIDS. 827 



modifications have arisen. Thus the Sedentaria are modified, as compared with most 

 errant forms, in the frequent reduction in number of the nephridia, in the differentiation 

 of the body-segments so as to form two or even three distinct regions, and in the 

 great development of the respiratory apparatus at the anterior end. But the purpose 

 of the last few pages will have been accomplished if, by the considerations I have 

 adduced, I have been able to show that the more sedentary Polychseta retain a number of 

 ancestral characters : — (l) in their sedentary and markedly cryptozoic habit ; (2) in the 

 correlated absence or slight development of the parapodia, and in the absence of jaws 

 and teeth ; (3) in the anatomy of the circulatory system ; (4) in the general occurrence 

 of intestinal respiration, and perhaps in the greater physiological value of the posterior 

 end of the body, — and, though these characters will make their appeal with different 

 degrees of force in different cases, to render it probable that the Sedentaria have a 

 better right than the errant members of the group to be recognised as the present-day 

 representatives of the ancestral form. 



REFERENCES TO LITERATURE. 



(1) Annandalb, N., " Notes on an Indian Worm of the genus Ghsetogaster," Journ. and Proc. Asiatic Soc. 



of Bengal, N.S., vol. i., No. 4, 1905. 



(2) "Some Animals found associated with Spongilla carteri in Calcutta," ib., vol. ii., No. 5, 1906. 



(3) Beddard, F., a Alonoyrajyh of the Order of OUgochxta, Oxford, 1895. 



(3a) " A new branchiate Oligochaete {Branchiura Soiverbyi)," Quart. Joiirn. Microsc. Set., N.S., 



vol. xxxiii., 1892. 



(4) Bknham, W. B., Art. "Polychaeta," in Cambridge Natural History, vol. ii., London, 1896. 



(5) BouNHiOL, J. P., " Recherches experimentales sur la respiration des Annelides," G. R. Acad. Sci. Pa? is, 



t. cxxxii., 1901. 

 (6) " Recherches biologiques experimentales sur la respiration des Annelides polychetes," Ann. Sci. 



Nat. (8), t. xvi., 1902. 

 (7) Short papers in G. R. Soc. Biol. Paris, t. Iv., 1903. 



(8) Bourne, A. G., "Notes on the Naidiform Oligochseta, etc," Quart. Journ. Microsc. Sci., N.S., 



vol. xxxii., 1891. 



(9) BousFiELD, E. C, "The Natural History of the genus Dero," Journ. Linn. Soc. (Zool.), vol. xx., 1890. 



(10) Bretschkr, K., " Beobachtungen Tiber die Oligochseten der Schweiz," Rev. Suisse Zool., t. x., No. 1, 



1902. 



(11) Carlgrbn, 0., " Ueber die Bedeutung der Flimmerbewegung ftir den Nahrungstransport bei den 



Actiniarien und Madreporarien," Biol. Gentralbl., Bd. xxv., 1905. 



(12) Cerruti, A., Abstract in Zool. Jakresb., 1907 : "Vermes," p. 67. 



(13) Darboux, G., "Sur le role physiologique des csecums intestinaux des Aphroditiens," Bull. Soc. Ntmes, 



t. xxvii., 1899. 



(14) DE St Joseph, M. le Baron, " Les annelides polychetes des cotes de Dinard," ^«w. Sci. Nat. {Zool.) 



(7), t. i., 1886. 

 (15) ib., t. v., 1888. 



(16) EisiG, H., "Ueber das Vorkommen eines schwimmblasenahnlichen Organs bei Anneliden," Mitth. Zool. 



Stat. Neapel, Bd. ii. Hft. iii., 1881. 



(17) "Die Capitelliden, " Fauna und Flora des Golfes von Neapel, xvi. Monographic, Berlin, 1887. 



