1918] Thoracic Sclerites of Dissosteira 361 



ginal region of the prescutum called the pretergite. Brooks 

 (p. 250) apparently interprets the alar ossicle "npo" as the 

 "patagium" (which is really an erectile lobe on the pronotum 

 of Lepidoptera, having nothing to do with the sclerite "np2," 

 although Brooks may have had the tegulse in mind, since the 

 tegulae are sometimes incorrectly homologized with the sclerite 

 "np2") and he homologizes the regions "JS2" and "po" (of 

 Fig. 3 of the present paper) with the "postscutellum." (See 

 also Fig. 32 of Melanoplus by Lugger, 1898). The true post- 

 scutellum of the mesothorax, however, is situated below the 

 region "po" and bears the characteristic longitudinal dorsal 

 muscles attached to the postscutellum of other insects, so that 

 the representative of a mesothoracic postscutellum is present 

 in grasshoppers, despite Snodgrass' statement to the contrary. 



Berlese, 1909. has discussed the tergal region of Acridium, 

 but, since I have no specimens of the species which he figures, I 

 am not sure that the regions into which he subdivides the 

 tergum correspond to those here given, especially since Berlese 

 doesn't homologize the sclerites correctly in different insects, 

 and as Snodgrass, 1909 (p. 535) very truly remarks "in order to 

 carry out his scheme, Berlese has in many cases drawn purely 

 arbitrary lines across the notum." Furthermore, Berlese 

 employs the prefixes "pro," "meso," and "meta" for sub- 

 divisions of one and the same segment instead of limiting the 

 prefix "pro" to prothoracic structure, "meso" tp mesothoracic 

 structures, and "meta" to metathoracic structures. Thus 

 " metatergite " to any one else would mean the tergite of the 

 metathorax, but Berlese applies this term to a subdivision of 

 the pronotum, mesonotum or metanotum indiscriminately, as 

 is also true of his terms " mesotergite " and "protergite." As 

 nearly as I can determine, the tergal subdivisions which he 

 describes in Acridium correspond to the following tergal sclerites 

 of the grasshopper here -discussed. 



In his Fig. 1, Plate IV, Berlese applies the term " acrotergite " 

 to the anteriormost tergite "pt2" of the mesothorax of the grass- 

 hopper (Fig. 3 of this paper) while he applies this same term to 

 the posteriormost tergite "psU" (Fig. 3) in the metathorax of the 

 grasshopper. In the mesonotum, he terms only the region 

 "sur2" the "protergite," and homologizes it with the entire 

 prescutum "pscs" in the metathorax. The scutum "sc" and 

 scutellum "si" comprise his "mesotergite" and the region 



