ANIMAL KINGDOM. 279 



are indebted for almost all we know of the internal organi- 

 zation of these animals. Before his works and the publica- 

 tion of M. Thomas of Montpelier appeared, the anatomy 

 even of the Leech was a subject of total ignorance to natu- 

 ralists. At present we are informed that four great blood- 

 vessels exist in this animal, which extend its whole length 

 and communicate with each other by lateral branches. 

 One of these vessels runs along each side, while of the 

 other two, one is dorsal and the other ventral. These last 

 apparently perform the functions of veins, and the former 

 two of arteries. This then is the general disposition to 

 which the system of circulation, more or less, approaches 

 in the Annelides, which are soft vermiform animals with 

 bodies wrinkled transversely or composed of annular seg- 

 ments. They are red-blooded like the Vertebrata, but with- 

 out a heart. It is a singular circumstance attending the 

 natural history of the Annelides, that their internal organi- 

 zation should have been understood long before their ex- 

 ternal structure ; in other words, that the usual course of 

 study should have been in them reversed. Now however, 

 thanks to the " Patientia" of M. Savigny, the natural 

 arrangement of this subsidiary division is as far advanced 

 as that of any other whatever. But unfortunately for the 

 scientific world the valuable Memoires of this author oil 

 the subject have not yet been published, and can be esti- 

 mated only by the extracts from them given in the 5th 

 volume of the " Histoire des Animaux sans Vertebres," 

 and by the Report of the Committee appointed by the 

 Institute to decide on their merits*. 



* I take this opportunity of gratefully acknowledging the obligation 

 which I am under to the friendship of M. Latreille, who from zeal to aid 

 this attempt to ascertain the natural situation of 5. sacer sent me the proofs 

 as they came from the press of two Mimoires, from which the reader will 



