38 Annals of the Carnegie Museum. 



Habitat. — Corumba, Brazil, and Asuncion, Paraguay (H. H. Smith). 



As suggested by the present writer in a former publication (Proc. 

 I . S. Nat. M us., XXX, p. 637) this insect is more or less aquatic in its 

 habits. It is also nocturnal and is best collected after night, wher. it 

 is attracted to bright lights. 



Family OMMEXYCHID^. 

 The representatives of the present family are medium-sized to large 

 locusts, with more or less strongly rugose, or even with spined, pronotum 

 and hind femora. They all belong to the South American continent, 

 where the majority of forms occur to the southward of the equator, 

 even entering the pampean region of Argentina as far as the Rio Negro. 

 The different species are frequently confined to special food-plants, 

 upon which they congregate in large numbers. 



The four genera belonging to the family are separated as follows: 

 Table for Determining the Genera of Ommexychid^e. 

 A. Body more or less graceful and cylindrical, somewhat rugose. The antennae 

 filiform. Pronotum feebly carinated. 

 b. Tegmina and wings fully developed, extending considerably beyond the 

 tip of the abdomen in both sexes. Carinae of hind femora smooth. In- 

 ternal angles of themesosternal lobes rounded at apex. Parossa nom. nov.' 

 bb. Tegmina and wings frequently abbreviated. Carinae of the hind femora 

 toothed or crenulated. Internal angles of the mesosternal lobes not 



rounded Ommexecha Serville. 



AA. Body very obese and greatly depressed; coarsely tuberculate, carinated, and 

 spined. Antennae with the joints somewhat flattened, subensiform. 

 Pronotal carina always more or less cristate. 

 b. Tegmina and wings present. Pronotum without lateral toothed, leaf-like 

 expansion; its hind border broadly angulated, and adorned with five 

 flat, tooth-like projections, the middle one furcate.. .Spathalium Bolivar. 

 bb. Tegmina and wings missing. Pronotum furnished at lower lateral edges 

 with a toothed, leaf-like expansion; its hind border broadly rounded, 

 and adorned with a series of six distinct, heavy, blunt spines. 



Grcea Philippi. 



Genus Parossa nom. nov. 

 Ossa Giglio-Tos (nee Motsch.), Boll. Mus. Zool. Anat. Torino, IX, no. 184, p. 15 



(1894). 

 Paulinia Kirby (nee Blanchard), Syn. Cat. Orthopt. Brit. Mus., Ill, p. 296, 



(1910). 



3 The insect described and figured by Blanchard (D'Orbigny, Voy. Amer. Merid. 



VI, No. 2, p. 216, pi. 27, fig. 6 (1843), and which Kirby considers congeneric with 



055a bimaculata and 0. viridis of Giglio-Tos, seems more likely to represent the 



Aerydium acuminata De Geer. Hence the suggestion of the name Parossa to 



eplace the preoccupied name 055a of Giglio-Tos. 



