186 FOURTH KBPORT — 1834. 



of Lutreille, the A)iuptura of Dr. Leach, and a portion of the 

 Entozoa of Rudolphi. Mr. MacLeay has endeavoured to show 

 that these five groups unite to form a circle. 



In Blainville's Principes, &c., we find the Aiinulosa forming 

 his third type, Entomozoaires * , which he divides into eight 

 chisses, characterized according to the presence or absence, 

 and when present the number or nature, of the appendages for 

 locomotion. The Annulosa with articulated feet he distributes 

 under the six classes Hexapodes, Octopodes, D^capodes, HeM- 

 ropodes, Tefradecapodes, and Myrkipodes ; the first including 

 the true Insects, the second the Arachnida of Cuvier, the third, 

 fourth, and fifth the Crustacea of that author. The inarticulated 

 Annulosa, comprising the Annelida of Cuvier, form his seventh 

 and eighth classes, called Clietopodes (with setiform appendages,) 

 and Apodes (deprived of appendages altogether). The last of 

 these two inclucles iilso some of the Entozoa. Few will pro- 

 bably be disposed to adopt this arrangement, which leads to di- 

 visions of very unequal value. 



In the Families Naturellcs of Latreille, the Annulosa (or, as 

 they are there termed, Condylopa,) are primarily divided into 

 the two sections of Hyperhexupi and Hexapoda, according as 

 the feet are more than six, or six only, in the adult state, the 

 former term being adopted from Savigny. The Hyperhexapi 

 include the three classes Crustacea, Arachnida, and Mi/riapoda, 

 this last being adopted from Dr. Leach, who first instituted it in 

 a paper read to the Linnaian Society in 1814 f. The Hexapoda 

 comprise the single class of Insecta. The Annelida are referred 

 by Latreille to a different branch of his arrangement of the 

 Animal Kingdom. 



Straus-Durckheim, in his Consid. Gen^r. sur VAnat. Comp. 

 des Anim. uirtic. published in 1828, considers the articulated 

 animals as including the five classes Annelida, Myriapoda, 

 Insecta, Crustacea, and Arachnida. To the end of the Intro- 

 duction of his work he has annexed two synoptic tables, in 

 which he has represented what he conceives to be the true chain 

 of affinities connecting these classes, and the principal groups 

 contained in them. It would, however, occupy too much room 

 to follow him in these details. 



In the Cours d' Entoniologie, published in 1831, Latreille 

 has adopted the same divisions as in the Fam. Nat. He only 

 substitutes the name of Apiropoda for that of Hyperhexapi. 



I shall now proceed to consider the progress and state of each 



* Tab. 7. t Linn. Trans., vol. xi. p. 306. 



