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few among those that show the different tendencies of creatures to- 

 wards the development of one or of the other pole. Beginning with 

 the development of the positive pole and ending with that of the ne- 

 gative, we find that animals come in the following order : — Vertebrata, 

 Mollusca, Articulata, Radiata. In Vertebrata, Mammalia and Aves 

 are represented by the positive pole, E-eptilia and Pisces by the 

 negative pole ; in Mammalia, Quadrumana and Carnivora are repre- 

 sented by the positive, Ruminantia, Cetacea and Marsupialia by the 

 negative ; in Aves, Rapacia and Zygodactyli by the positive, Palmi- 

 pedes and Pinnatipedes by the negative ; in Reptilia, Chelonia and 

 Sauria by the positive, Ophidia and Batrachia by the negative; in 

 Pisces, Cyclostomi and Plectognathi by the positive, Acanthopterygii 

 and Plagiostomi by the negative. Mollusca have the following order 

 from the positive to the negative pole : — Cephalopoda, Pteropoda, 

 Gasteropoda, Acephala ; and in Articulata the same order will be 

 thus, — Crustacea, Ai'achnida, Insecta, Myriapoda; and in Crustacea 

 the Decapoda tend more to the positive pole, and the Isopoda, Si- 

 phonos toma and Xiphosura to the negative pole ; in Arachnida the 

 Pulmonata approach the positive, the Tracheata the negative pole ; in 

 Myriapoda the Chilopoda are positive, and the Chilognatha negative. 

 The transition of insects from one pole to the other is very remarlca- 

 ble ; their early life, or the larva state, tending to the development of 

 the negative pole, then the abdomen occupies the greater part of the 

 body, but when the insect attains its perfect state the size of the ab- 

 domen is diminished, its appendages often cease, the head and other 

 segments adjoining the positive pole acquire the greatest development. 

 Among Insecta the Coleoptera have generally the greatest tendency 

 to the superior pole, and especially the Cicindelites, Carabites, Dytis- 

 cites, Staphylinites and Telephorites, but compared to these the Sca- 

 rab8eites,Ceramby cites, Curculionites and Chrysomelites, belong rather 

 to the inferior pole. In the Orthoptera, the Achetites and Mantites 

 present examples of the first class, and the Locustites and Phasmites 

 of the second. Of the Neuroptera, the Phryganiites, Ephemerites 

 and Panorpites are claimed by the lower pole, but the Libellulites, 

 Termites and Raphidiites by the upper pole, which in the Hymenop- 

 tera begins with the Formicites, is continued through tlie Fossoria 

 and the other Aculeata ; next come the Pupivora ; and lastly the 

 tribes from Sirex to Cimbex, which manifest most of the contrary 

 tendency. The lesser groups of this class also diverge the one fi'om 

 the other in opposite directions, such as the Ichneumones genuini 

 from the Ichneumones adsciti, Anacharis from Cynips, Dryinus from 



