THE THORACIC SCLERITES OF THE GRASSHOPPER 

 DISSOSTEIRA CAROLINA* 



By G. C. Crampton, Ph. D. 



There is perhaps no insect which is studied more frequently 

 than the grasshopper, since the drawing of its structural details 

 has served as an introduction to entomology for "generations" 

 of students; yet the parts of its thorax have been surprisingly 

 misinterpreted in practically all text-books and other pubUca- 

 tions in which it has been described. 



Since the incorrect figures and descriptions of the grass- 

 hopper's anatomy have been so widely copied in various text- 

 books, (the figures by Packard, 1898, having received the 

 widest acceptance) and other publications, it has seemed 

 advisable to make a further study of the structural details of 

 this insect, with a view to determining what interpretation of 

 the parts is the correct one. For this purpose, the thoracic 

 structures of Dissosteira Carolina, L., have been selected to 

 illustrate the points to be considered in the following discussion, 

 since this insect is as little modified as any of our common 

 grasshoppers, and is among the largest (and hence the most 

 easily examined) of the forms whose wide distribution makes 

 them available to everyone for study. 



In order to avoid the distortion due to the shrinking of 

 dried material, only such specimens as have been preserved in 

 alcohol, or similar preserving ^uids, have been used, and in 

 examining them, it has proved more satisfactory to keep the 

 specimens immersed in a liquid medium (alcohol or water) and 

 to illuminate the field of the binocular (which is the most 

 satisfactory microscope for dissection work) by means of a 

 nitrogen-bulb lamp provided with a condenser. 



PROTHORAX. 



The prothorax is the only thoracic segment which has 

 remained freely mobile, the meso- and metathorax being rather 

 closely united, although the line of demarcation between them 



* This paper is one of a series of contributions from the Entomological Labora- 

 tory of the Massachusetts Agricultural College, dealing with the anatomy of the 

 grasshopper Dissosteira Carolina L. 



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