GROUPING OF INSECTS. 



105 



The following diagram shows, in a rude way, the relative 

 rank and affinities of the eight orders, and of the two series 

 of Six-footed Insects. 



Neuroptera. 

 Thysanura. 



Through Lepisma, and Podura which are wingless Thysa- 

 nurous insects, the lower series is connected with the Myriopods, 

 the minute degraded Pauropus and Scolopendrella perhaps 

 forming the connecting links; and through the wingless 

 flies, Braula, Chionea, and Nycteribia, the Diptera, belonging 

 to the higher series, assume the form of the Spiders, the head 

 being small, and sunken into the thorax, while the legs are 

 long and slender. The first and highest series culminates in 

 Apis, the Honey-bee ; and the second, or lower, in Cicindela, 

 the Tiger-beetle. 



regarding the rank and value of the minor groups. Professor Agassiz extended 

 Leuckart's views in considering the seven grand divisions of the order of Hexapods 

 as suborders. In 1803 (How to Observe and Collect Insects, Maine Scientific Sur- 

 vey, and Synthetic Types of Insects, Boston Journal of Natural History), we 

 proposed a new classification of these divisions, by which they are thrown into 

 two main groups headed by the Hymenoptera and Coleoptera respectively. These 

 two groups, as represented in the diagram, are nearly equivalent in value, and 

 stand in a somewhat parallel relation. There is nothing like a linear series in the 

 animal kingdom, but it is like a tree. The higher series of orders form more 

 of a linear series than the lower series, so that in the diagram the Neuroptera, 

 Orthoptera, Hemiptera, and Coleoptera form a more broken series than the Hy- 

 menoptera, Lepidoptera, and Diptera. A Bee, Butterfly, and House-fly are much 

 more closely allied to each other than a Beetle, a Squash-bug, a Grasshopper, 

 and a Dragon-fly are among themselves. The Neuroptera are the most indepen- 

 dent, and stand at the bottom of and between the two series, though by the Orthop- 

 tera they are very intimately linked with the Hemiptera and Coleoptera. 



