16 



HKTIIOI'TKRA OF NORTHEASTERN AMERICA. 



smell. They vary much iu length and form among the different 

 families of Orthoptera, the variation being the result of adapta- 

 tion to their peculiar surroundings and habits. For instance, in 

 those camel crickets (CeuthopMlus) , which dwell in caves, they 

 are very much longer than in those members of the same genus 

 which dwell above ground. Characters pertaining to their form, 

 length, and point of union with the head, are much used in classi- 

 fication. Such terms as filiform, clavate, setaceous, etc., relating 

 to their form, are defined in the accompanying glossary. 



Characters pertaining to the vertex, or that part of the epicra- 

 nium, between the eyes, are much used in separating the different 

 species of Orthoptera. The central portion of the vertex, known 

 as the disk (r/r) or wntc11iint (ftr) is often depressed, or sepa- 

 rated from the remainder. Its bounding walls are 

 termed lateral carince and often a median carina di- 

 vides it into two parts. The front portion, or apex, 

 often called the fastigiuin, is variable in form and its 

 characters are also much used. On the outer side of, 

 and a little below the front half of each lateral carina 

 of the vertex there is, in many Orthoptera, a little 



Fig. 4. Show- 

 ing fastigium, space or concavitv bounded bA 7 elevated ridges. These 



disk and foveo- 



ix of vertex, spaces are the lateral fovcolce (f.) and their varia- 



( After L u g- 



gerj tions in size and form also afford characters much 



used in classification. 



THE THORAX AND ITS APPENDAGES. The middle region of the 

 body of a locust or other insect is called the tliora.r. To study its 

 parts aright, the wings and legs attached to it should be removed, 

 when it will be seen to consist of three rings or segments. These 

 are known as the protliorax, mesothorax and metathorax. With- 

 in these rings are located the muscles for moving the wings and 

 legs, as well as some of the digestive organs. 



The prothorax of the locust (Fig. 5) has its entire dorsal 

 surface, and sides in great part, covered 

 by a large sunbonnet-shaped piece known 

 as the pronotnin (pro). This varies 

 much in shape and size in the different 

 families of Orthoptera. Its upper sur- 

 face is called the disk, and its sides the 

 lateral lobes. Raised lines known as the 

 lateral carina: usually separate the disk 

 from the sides, while often a third line, 

 the median carina runs lengthwise through 

 the middle of the disk. 



Fig. 5. 

 prothorax 



Side view of 

 of a locust 



(After Lugger.) 



