METAZOA INSECTA. 475 



121 1) has deep, rich hues and is one of our common New 

 England butterflies. 



One of the most magnificent genera is Morpho, some of 

 whose species are regal in their coloring. Morpho 

 epistrophis Hiibn. (No. 1212) is an exquisite light blue 

 species. 



Order 15. HYMENOPTERA. 



The Hymenoptera and the following order, the Diptera, 

 are extremely interesting, since the former illustrate better 

 than any other order of insects specialization by addition, 

 and the latter specialization by reduction. 



Partly because of the many adaptive organs possessed 

 by Hymenoptera and partly on account of their remark- 

 able physiological development, reaching in the case of 

 ants an intelligence which differs from that of man only 

 in degree and not in kind (Lubbock), the order Hymen- 

 optera has been placed by many entomologists at the head 

 of the insect group. In a natural classification, however, 

 it is evident that that order of insects which is farthest 

 removed, both in its larval and adult structural features, 

 from the primitive ancestral stock-form is the one entitled 

 to the position of the most specialized of its kind. It 

 will be seen (p. 493) that the young and full grown Dip- 

 tera are unquestionably farther removed from the Thy- 

 sanuriform type of insect than these stages of other orders 

 and for this reason the Diptera are placed last in our 

 Synoptic Collection of insects as representing the acme 

 of specialization. 



Terebrantia, or boring Hymenoptera. The larvae of the 

 Hymenopterous family of saw-flies, Tenthredinidae, are 

 caterpillar-like in form and general characters, as seen in 

 the violet sawfly, Emphytus canadensis Kby. (PI. 1213, 

 fig. i, x 4). The active larva is provided with biting 

 mouth pirts, jointed thoracic legs, and eight pairs of prop 



