ACEIDIIKS. 211 



30 (23). Fastigium of the vertex obtuse. The frontal costa neither 



compressed nor sulcate. Median carina of the pro- 

 notum elevated into a crest cut into lobes by the sulci. 



31 (36) . Posterior tibiae provided apically on both sides with a spine. 



32 (35). Interocular space of the vertex narrower than the length 



of the eyes. 



33 (34). Tegmina densely reticulate, without intercalary veins 



between the branches of the radials Titanacris, Scudder. 



34 (33). Tegmina less densely reticulate, provided with intercalary 



veins between the branches of the radials Tropidacris, Scudder. 



35 (32). Interocular space of the vertex as wide as, or wider than, 



the length of the eyes. Frontal costa very broad, above 



the antennae dilated, not sulcate . Prionacris, Stal. 



36 (31). Posterior tibiae without apical spine on the outer margin. Nichelius, Bolivar*. 



37 (22). Wings with the part immediately back of the humeral 



area not dilated or furnished with parallel transverse 

 veins. Fastigium of the vertex produced, angulately 

 contiguous with the front. 



38 (57). Mesosternal lobes distant. 



39 (56). Frontal costa below the ocellus wanting or evanescent. 



Second joint of the hind tarsi elongate. 



40 (55). Pronotum with the metazona shorter than the prozona. 



41 (46). Interocular space of the vertex very narrow, narrower 



than the frontal costa. Costal border of the tegmina 

 widely membranous. 



42 (43). Frontal costa between the antennae strongly produced, 



as seen from the side rounded Nautia, Stal. 



43 (42). Frontal costa between the antennae only gently or 



moderately produced. 



44 (45). Face and pronotum densely, strongly punctate .... Ophthalmolampis, Stal. 



45 (44). Face and anterior lobe of the pronotum smooth or 



sparsely, faintly punctate T^eniophora, Stal. 



46 (41). Interocular space of the vertex wider, at least equal to 



the width of the frontal costa. Costal border of the 

 tegmina, when present, reticulate or veined. 



47 (48). Pronotum elevated posteriorly Mezentia, Stal. 



48 (47) . Pronotum not elevated posteriorly. 



49 (50). Interocular space of the vertex of equal width with, or 



slightly wider than, the frontal costa, the latter deeply 



sulcate Hisychius, Stal. 



* According to Bolivar (' Enumeration des Orthopteres de l'ile de Cuba,' p. 29) tlie representatives of the 

 genus Nichelius do not have an apical spine on the exterior margin of the hind tibiae, although by other 

 characters it would be necessary to class it in the section provided with the spine. 



2 Ee2 



