152 f'OURTH UEPORT — 1834. 



A slight moditiciitiou of Geoffroy's views has been adopted by 

 M. Dumortier, and recently published in a memoir on the com- 

 parative structure of plants and animals, in the 16th vol. of 

 the jVov. Act. S)C. Nat. Cur.'*. Like Geoffro)^, he considers 

 the hard parts of Crustacea and Insects as strictly analogous to 

 the osseous system of the Fertebrata ; but instead of the two pri- 

 mary groups into which he distributes animals, M. Dumortier 

 would adopt the three divisions oi Endosceleta, Exosceleta, and 

 Asceleta, the second answering to Geoffroy's Dernio-Vertthres, 

 and the third to his Invertebres. These are given in a tabular 

 form, with the secondary groups into which he thinks the animal 

 kingdom shbuld be divided, amounting to twelve in number, also 

 annexed. In a former part of his paper, M. Dumortier has 

 entered into considerable details on the subject of the analogies 

 which may be observed between the above three primary groups 

 of animals, and the corresponding primary groups in the vege- 

 table kingdom. It would, however, occupy too much room to 

 enter into any more extended analysis of his views. 



In 1821, Mr. MacLeay published the second part of his Horce 

 EiitoinologiccB, in which he proposed a new arrangement of the 

 leading groups of the animal kingdom, and considered them as 

 referrible to five primary types, instead of four, the number 

 adopted by Cuvier. The new type, which he has called Acrita, 

 he intended should include the least organized of the Entozoa 

 of Rudolphi, as well as Cuvier's classes of Folypi and Infusoria, 

 all which he considered as not sufficiently showing the true ra- 

 diated structure characteristic of the type to which Cuvier referred 

 them. Mr. MacLeay observed, that the necessity for this step had 

 been previously pointed out, though indirectly, by Lamarck and 

 Blainville. The establishing of this new group was not, however, 

 the most importantfeature in the Horce Entomologicce. Mr. Mac- 

 Leay announced some new principles connected with the clas- 

 sification of animals, which, from the circumstance of their having 

 led to a peculiar school of zoologists in England, it will be ne- 

 cessary to consider a little more in detail. The most important 

 of these principlesf are : 1st, That all natural groups, of ichut- 

 ever detioinination, return into themselves, forming circles; 

 iindly, That eachof these circular groups isresolvahle intoexactli/ 

 Jive others; 3rdly, That these Jive groups always admit of a 

 binary arrangement, two of them being what he calls tj'pical, 

 the other three aberrant; 4thly, That while proximate groups 



* p. 306. 



t It may be observed, that Mr. MacLeay lias nowhere formally stated these 

 principles as above. They are only gathered I'rom what he has written on the 

 subject. 



