MEMOIR OP LATREILLE. 31 



being of insects, is still merely artificial, that it is not 

 sufficiently strict, for the order of the Suctoria is an 

 apterous group, not in its right place among the 

 Insecta Pterodicera. And also the groups which 

 are here considered as equivalent to the Tetracera, 

 Myriapodct, Apterodicera, and Pterodicera, are by no 

 means of equal value, but the two first and two last 

 are most closely allied ; the former are the subordi- 

 nate members of a higher group, and the latter also 

 could at most be placed as equivalent to the orders 

 of the Insecta pterodicera." 



Before leaving this subject, it may be desirable to 

 show briefly, in juxta-position with the above, some 

 of the various changes our author afterwards made in 

 his arrangement, for in every successive work im- 

 portant alterations were effected. In his " Conside- 

 rations generates sur l'Ordre Naiurel des Animaux 

 composant les Classes des Crustaces, des Arachnides, 

 et des Insectes," * the Linnean Insecta was divided 

 into three equivalent groups, Crustacea, Arachnides 

 (including the Insecta aptera of the fonaer system), 

 and Insecta. Such was likewise the arrangement 

 which appeared in Cuvier's Iiegne Animal t, but 

 the groups were differently defined, and some of the 

 contents of each transferred to another. There was 

 likewise the necessary addition of the order Strep- 

 siptera, recently discovered by Kirby. After seve- 

 ral other changes, of more or less importance, in 

 different works, we come to that embodying his 

 latest views, published in his " Cours d'Entomo- 

 logie,"^ which was completed only a short time before 

 * Paris, 1810, 8vo. + Paris, 1817. X Paris, 1832, 8vo. 



