Bruner: Soi mi American Acridoidi \. 69 



plainl) dentate. Outer margin oi the hind tibiae with six spines 



in addition to the apical spine. Prosternal spine small, slender, 

 conical on a broad hca\ > base. 



Length of body, ?, 33 nun., of pronotum, 6 nun. of hind femora, 

 ni mm. 



Habitat. Para. Brazil, a single 9 , where it was taken during 

 the month of April by II. II. Smith. The type is deposited in the 

 Carnegie Museum. 



Group LKPTYSM.E and Allies. 

 There are in America a number of genera of long-winged, slender, 

 cylindrical locusts, of nearly uniform greenish color, which have 

 the margins of their hind tibia' developed into more or less acute 

 lamelhe. which aid these semi-aquatic locusts in swimming, when, ac- 

 cidentally or otherwise, they rind themselves in water. The following 

 table is an attempt at a preliminary arrangement of the genera. 



Table for Separating tiiic Genera of Leptysm-e and Allies. 

 .1. Posterior tibiae slightly expanding apicaUly, the margins acute. 



b. Mesosternal lobes with their inner margins nearly straight and touching for 

 most of their length. Tegmina acuminate. 

 c. Fastigium of the vertex as long as. or longer than, the longest diameter of 

 the eyes. 

 d. Fastigium of the vertex provided with decided longitudinal grooves 

 or sulci. 

 e. The vertex furnished with but a single longitudinal groove. 



/. Form of insect cylindrical, the fastigium with its sides rounded, 

 and the median sulcus of nearly equal width throughout. 



Leptysma Stal. 

 ff. Form of insect more robust, the fastigium with its sides straight, 

 and the median sulcus narrowing rapidly behind. • 



Columbacris gen. now 

 ee. The vertex furnished with more than one longitudinal groove. 



f. Vertex with four such grooves Leptysmina Giglio-Tos. 



ff. Vertex with many grooves Oxyphyma Saussure. 6 



dd. Fastigium of the vertex without definite longitudinal grooves or 



sulci Cylindrotettix Bruner. 



cc. Fastigium of the vertex shorter than the longest diameter of the eyes. 



Stenacris Walker. 



6 The genus Oxyphyma Saussure (Rev. Zool., XIII, p. 156, 1861) is placed in this 

 group on the authority of \Y. F. Kirby (Syn. Cat. Orthopt., Ill, p. 412, 1910). 

 ne's description is so meager, however, that its exact location is somewhat 

 problematical. The habitat of Saussure's insect is also doubtful. 



