272 Mr. Newport on the Class Myriapoda, Order Chilopoda, 



brain of Vertebrata, are those parts of the nervous system which indicate high 

 development. The relatively greater development of these parts, as compared 

 with that of the other portions of the nervous system in the different classes of 

 the Articulata, seems to indicate that Insects, as a class, are superior to the 

 other classes. In support of this view I need but refer to the great develop- 

 ment of the cerebral portion of the nervous system in the gregarious Hymen- 

 optern, so remarkable for their half-reasoning intelligence. In these insects 

 the development of the brain, as compared with that of the other parts of the 

 nervous system and of the body, exceeds that of any of the other Articulata. 

 The perfection of organization, as seen in the most perfect forms of the Verte- 

 hrata, is the performance of the- voluntary functions of the body by the most 

 concentrated means. A relatively inferior size of the cerebral portion of the 

 nervous system, and an increased number of organs of locomotion, may thence 

 be regarded as proofs of a lower type of development. This view is supported 

 by the small size of the cerebral ganglia and by the existence of abdominal 

 legs for locomotion in the larvae of Insects. These cerebral ganglia are always 

 increased in size, and the abdominal legs have entirely disappeared when the 

 insect has arrived at its perfect state, in which its voluntary powers are greatly 

 augmented, and its organs of locomotion are concentrated in the thoracic region 

 of the body. It may be urged, in opposition to this view, that an accumula- 

 tion of nervous matter on the ventral surface of the body exists also in the 

 Arachnida and Crustacea ; but there is no correspondent enlargement in 

 these classes of those portions of the nervous system, the supra-cEsophageal 

 ganglia, on which the instinct and intelligence of the animal seem entirely 

 to depend, wiiile the increased number of organs of locomotion indicates in 

 them a lower type of formation. 



These are the considerations which induce me to place the Articulata at the 

 head of the Invertebrata, and the hexapod Insects above the Arachnida and 

 Crustacea. The many analogies that exist between the Crustacea and the 

 Myriapoda, both in external form and in the structure of some of their in- 

 ternal organs, show the close affinity of these two classes. On the other 

 hand, the manner in which the Myriapoda are developed on their leaving the 

 ovum, and the periodical formation of new segments to the body, show their 

 near approach to the Annelida. 



