224 



FAMILY VI. ACRIIUD.E. THE LOCUSTS. 



vertex, but invisible from above; frontal costa rather high, often 

 sulcate only in the region of the ocellus; antenme filiform, some- 

 times feebly depressed and acuminate; pronotum with median 

 carina sharp, cut in or just behind the middle, its lateral carinse 

 diverging both on prozona and metazoua so that the center of 

 disk is notably narrower than either the front or hind margin; 

 lateral lobes no longer than high, their front margin oblique, 

 nearly straight, hind one less oblique, more or less sinuate, lower 

 one plainly angulate near middle, its front portion strongly as- 

 cending; tegmiua very narrow, the intercalary vein wanting, the 

 upper ulnar vein apically joining the lower uluar much beyond 

 the end of baso-discal field ; hind femora of medium size, surpass- 

 ing tip of abdomen ; hind tibia3 with 10 to 12 spines on outer mar- 

 gin, their inner apical spurs subequal; subgenital plate of male 

 shorter than preceding segment, its apex broadly rounded ; valves 

 of ovipositor moderately exserted. 



An American genus of large size to which Kirby (1910, 119) 

 accredited 41 species, 13 from the United States, the others from 

 the West Indies, Mexico, Central and South America. It is the 

 most widely distributed genus of North American Tryxalinie, and 

 the most abundant in species. However, only four are definitely 

 known from the Eastern States. 



f 



Fig. 84. Structures of Tryxalirue. a, Ensiform antenna; of Pseudopomala; b, same 

 of male of Try.valis; c, head of Chorthippus, showing foveola; d, tip of female abdomen 

 of Chlccaltis abdominalis; e and /, dorsal views of head and pronotum of Orphuclla 

 olh'acea; g and h, same of O. pelidna; i and /, same of O. speciosa. (After Morse.) 



KEY TO EASTERN SPECIES OF ORPHITLELLA. 



a. Lateral carina? of pronotum distinctly more widely separated at hind 



margin than at front one; vertex in both sexes with its apex acute 



or rectangular (Fig. 84, e to 7i); lateral foveolae distinct; tegmina 



longer than abdomen. 



l>. Prozona and metazona subequal in length; antenna? as long as 



