OLIGONYX.-— HAKPAGONYX. 175 



6. Oligonyx toltecus, sp. n. 



2 ■ Pulvo-grisea, nigro-punctata, gracillima. Frons utrinque macula nigra ; vertex subrectus, lobis lateralibus 

 parum prominulis. Prothorax elongatus, gracilis, nigro-irroratus, sparse granulatus, marginibus tenuiter 

 dense acute denticulatis. Pars posterior quam pars anterior fere duplo longior. Collum angustum, magna 

 parte parallelum, retro dilatatum. Pedes antici gracillimi, fusco-fasciati vel maculosi et punctati ; coxae 

 retro fere ad basin prothoracis attingentes. Tibiae spinis validis armatse, intus ante spinam primam 

 dentulis 2 instructae. Abdominis apex sensim ut in 0. mexicano, lamina supra-anali tamen longiore, 

 valde carinata. 

 Long. 43 ; pronot. 12*5, femor. ant. 9, lam. supra-anal. 3 - 2 millim. 



Bab. Mexico, Chilpancingo in Guerrero 4600 feet (R. H. Smith). 



This insect is perhaps the female of 0. mexicanus (?), the proportions of the coxae and 

 prothorax being about the same. 



HAEPAGONYX*, Sauss. 

 Harpagonyx, Saussure, Societas Eutomologica, 1892, p. 122. 



Caput parum latum ; vertice valde compresso, acuto, bidentato ; fronte plus minus planata, tricarinulata. 

 Prothorax gracilis, modice longus, denticulatus, ampliatione tenui. Pedes antici graciles. Coxse ultra 

 medium subcompressae, margine superiore sublamellari, ultra medium subcompresso, subsinuato, dehinc 

 lamellari. Femora gracilia, in dimidia parte apicali spinosa ; margine interno spinis 6-8 inaequalibus 

 armato, ultima remota. Spinulae subapicales obsoletae. Spinae discoidales 3 longiusculae (prima deficiens). 

 Tibiae breves, teretes, subtus haud sulcata3, spinis intus 3, quarum 2 prima? a basi curvatce, oppresses, tertia 

 elongata subrecta, ad superum dejecta, divergens. Lamina supra-analis elongato-trigonalis. 



S £ . Elytra et alae illis generis Olygonichis conformia. 



In this genus, as in Thesprotia, the armature of the anterior tibiae is nearly reduced 

 to the claw. The outer spines are rendered useless in a most extraordinary way by 

 their curving back against the tibia. (Tab. VIII. fig. 4 b.) 



In this very curious type the anterior tibiae are armed, as in Oligonyx, with only four 

 spines ; but the two spines of the inner margin are curved against the tibia, with their 

 points applied against its inferior face (comp. Tab. IX. fig. 21), so that they seem to be 

 of no use for capturing prey. The single spine of the exterior margin is quite apical, 

 it being placed under the point of insertion of the tarsus f ; it is, however, sometimes 

 obtuse or atrophied. The claw and upper spine appear to be the only weapons that can 

 be used for grasping purposes. 



It would be interesting to know how these insects capture their prey, and for what 

 purpose the inner spines have their points recurved against the tibia, so as apparently 

 to render them useless. 



* aptral, ferocious ; ovvi,, claw. 



t This spine is often difficult to detect : it is best seen by examining the tibia from its inner face and 

 somewhat from below. 



