REHN AND HEBARD 115 



G. Head broader. Pronotum with the disk 

 broader in proportion to its length, caudal 

 margin of disk roundly obtuse-angulate to 

 rectangulate gracilipes (Thomas) 



GG. Head narrower. Pronotum with the disk 

 narrower in proportion to its length, caudal 

 margin of disk acute-angulate. 



gracilipes constricta Brunner 



Arethaea arachnopyga^^ new species (Figs. 36, 50, 60 and 61.) 



This species, in certain respects, occupies as unique a position as 

 A. phantasma, having no very close relationship to the other forms 

 of the genus. The male can immediately be distinguished from 

 all of the other forms by the larger, longitudinally sulcate supra- 

 anal plate, the margin of the disto-dorsal abdominal segment being 

 deeply emarginate to receive the plate. From A. semialata, to 

 which it bears a more pronounced superficial resemblance than to 

 any other, the present form can, in addition to the character given 

 above, be separated by the narrower disk of the pronotum, the 

 more acute-angulate caudal margin of the disk, the more obUque 

 caudal margin of the lateral lobes of the pronotum, the less exten- 

 sive stridulating field of the male tegmina, which in general more 

 resembles that of gracilipes, and by the heavier ovipositor. 



The male sex in many features is very close to A. gracilipes con- 

 stricta, but the genital characters are different and the female is 

 moderately brachypterous instead of macropterous as in gracilipes. 



Type. — & ; Marathon, Brewster County, Texas. Elevation 

 3940 to 4160 feet. August 26 to 27, 1912. (Rehn and Hebard.) 

 [Hebard Collection.] 



Description of Type. — Size medium; form moderately compressed. Head 

 with the greatest width, which is immediately ventrad of the eyes, contained 

 one and one-half times in the depth of the head; occiput rounded, moderately 

 declivent to the fastigium; fastigium narrow, lanceolate, acuminate, sulcate 

 medio-longitudinally, apex subdepressed; frontal fastigium briefly truncate 

 dorsad and in contact with the fastigium of the vertex; eyes prominent, 

 elliptical, the greatest width about two-thirds the greatest depth, the latter 

 subequal to the depth of the infraocular portion of the genae; antennae more 

 than three times the length of the body. Pronotum considerably com- 

 pressed, the lateral lobes somewhat expanding caudad when seen from above, 



^^ Apaxvris spider, Trvyr) buttocks; in allusion to the resemblance of the 

 supra-anal plate of the male to the jaws of a spider. 



TRANS. AM. ENT. SOC, XL. 



