640 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxx. 



GR^^A Philippi. 



This fourth genus of the subfamily is also liable to occur in Para- 

 guayan territor}'. But two species are known to the writer, and both 

 of them are found on the pampas of Argentina from Bahia Blanca to 

 Catamarca and northward. Gra^a horrlda Philippi is shown on 

 Plate XXXVII at fig. 1. 



Subfainily ^ORIDIIN'.^E. 



This is by far the most extensive subfamily of locusts represented 

 in the region covered by the present paper, and contains, with but two 

 or three exceptions, all of the destructive species. The following 

 rather long table for the separation of the genera to which these 

 insects belong will be of some value to the reader in separating the 

 many forms that occur in any particular region. In genera Avhere 

 more than one species occur there will also be found tables for the 

 separation of the different species. 



TABLE FOR DETERMINATION OF GENERA. 



o. Posterior tibife provided with an apical spine above on botli margins. 

 h. Fastigium of the vertex horizontally greatly produced, 

 c. Tegniina somewhat surpassing the tip of the abdomen, their apex truncate. 

 Superior carina of the hind femora terminating at the apex in a prominent 



tooth Procolpia Stal 



cc. Tegiuina considerably surpassing the tip of abdomen, their apex narrowly 

 rounded. Superior carina of hind femora terminating in a small tooth. 



Munatia Stal 



d. Crest of the ])ronotum serrate throughout Prionolopha Stal 



dd. Crest of the pronotum not serrate, or sometimes posteriorily crenulate, or 

 somtimes cut by the transverse sulci. 

 e. Lateral carinie of the pronotum converging toward the front. 

 /. Carinje of the frontal costa i)arallel or gently diverging above the ocellus. 

 g. Tegmina and wings complete, equaling or surpassing the abdomen. 



Tropinotus Serville 



(j<l. Tegmina and wings a])breviated Alcamenes Stal 



//. Carinii' of the frontal costa <liverging above the ocellus. 

 ee. Lateral carina' of the pronotum parallel or diverging toward the front. 



Elnochlora Stal 

 hb. Fastigium of the vertex sloping or depressed. 



c. Wings with that portion just back of the vein whii'h divides the first and 

 second parts dilated and provided with numerous parallel transverse veins. 

 (/. Fastigium of the vertex subtriangularly acuminate. Frontal costa com- 

 pressed. Pronotum above rounded; lateral carina obliterated in front of 



last transverse sulcus, blunt back of it CJiromacriK Walker 



dd. Fastigium of the vertex obtuse. Frontal costii not compressed or sulcate. 

 e. Median carina of the pronotum not cristate. Head somewhat smooth. 



Frontal costa above tlie antenn;e obtusely sulcate Zoniopoda Stal 



ee. Median carina of the pronotum ielevated into a crest which is interrupted 

 by the sulci so as to form lobes Tropidacris Scudder 



