IDIAETHE01S'. 425 



2. Femina. 



a. Ovipositor dimidia parte postica tota nigra. Lamina infra-genitalis incisa. 



b. Laminae supra-analis processus valde angustus, tseniiformis, elongatus, ad inferum 

 cochleatus, corneus, pallidus. Statura plerumque major. — 1. incurvum. 

 bb. Lamina supra-analis plana, haud incurva. 



c. Lamina supra-analis longiuscula, cornea, nitida, basi nigro-foveolata. 

 d. Lamina supra-analis subparallela, apice tridentata. — 2. furcatum. 

 dd. Lamina supra-analis elongato-trigonalis, apice angusta, truncata. — 3. atrispinum. 

 cc. Lamina supra-analis quadrata, coriacea, subexcavata, punctata, pallida — 1. sub 

 quadratum. 

 aa. Ovipositor margine inferiore toto pallido. Lamina infra-genitalis ? subquadrata. — 5. swb- 

 notatum, Br. 



1. Idiarthron incurvum, Stal. (Tab. XX. %g. 13-15.) 



Meroncidius incurvus, Stal, Obs. Orthopt. 1 (Bib. till Svenska Vet.-Ak. Handl. iii.), p. 41 (1875). 

 Idiarthron incurvum, Brunn. v. W. Monogr. der Pseudophyll. p. 172, t. 7. fig. 77 c (c?). 



Majus, fulvo-griseum, unicolor. Pronotum verruculoso-granulatum ; margine antico plus minus tuberculato, 

 postico leviter arcuato. Elytra venis punctis brunneo-circumdatis et areolis marginis antici fuscis necnon 

 maculis brunneis minutis ad conjunctionem venarum notata. Ala3 pallide infuscatae. Coxae supra nigro- 

 marginatas. Femora 1, 2 spinis 4, apice nigris ; postica spinis 7, totis nigris. 



2 . Lamina supra-analis basi transversa, subabscondita, in medio processum taeniiformem parallelum ad inferum 

 cocbleatum, apice truncato-subincisum, vel subtridentatum formans (fig. 13, s). Lamina infra-genitalis 

 trigonali-incisa. Ovipositor elongatus, gracilis, rectus, margine superiore leviter sigmoidali, inferiore 

 parum arcuato, dimidia parte apicali nigra. 

 Var. a. Spinas femoram 1, 2 tota? nigrae sieut in /. atrispino. — h. Tense elytrorum concolores. 



<3 . Campus tympanalis sinister nigrescens vel niger, opacus. Segmentum anale truncatum, utrinque spinosum. 

 Lamina supra-analis processum angustum basi curvatum, ad inferum valde deflexum, supra ubique 

 punctatum formans; hie basi angustus, apice infundibuliformiter dilatatus, margine postico trilobato, 

 lobo medio trigonali, lobis extends rotundatis. Cerci teretes, brevissimi, arcuati, crassissimi, apice minute 

 unguiculato, vel rotundato vel atbenuato. Lamina infra-genitalis elongata, angusta, in medio longitudi- 

 naliter depressa, rugulosa, anguste incisa, ; stybs apicalibus longissimis, valde deplanatis, submembranaceis, 

 apice breviter attenuatis, rotundatis (lamina infra-genitali longioribus). 



Var. <5 . Processus laminae supra-analis obsolete sulcatus, margine apieali plus minus trilobatus vel vix 

 tridentatus. 



5 . Long. corp. 37 ; pronot. 10-5 ; elytr. 43*5 ; femor. post. 29 ; ovipos. 24 millim. 



$ . Long. corp. 30 ; pronot. 8 ; elytr. 32 ; femor. post. 22-5 ; ovipos. 17 millim. 



S . Long. corp. 32 ; pronot. 9 ; elytr. 35-5 ; femor. post. 25 millim. 



Figttkes :— Fig. 13, the apex of the abdomen, $ , in profile : s, supra-anal plate ; c, cercus. — Fig. 14, ditto, from 

 aDO ve. — Fig. 15, the supra-anal plate of the male, from above : s, supra-anal plate ; a, anal segment. 



Hab. Panama, Chiriqui. — Venezuela ; Amazons. 



This species is well characterized by the extraordinary form of the supra-anal plate, 

 this being somewhat similar in both sexes, but much shorter in the females than in 

 the males. The cerci are obtuse and conical ; they generally embrace the supra-anal 

 plate so as to completely conceal it. 



2. Idiarthron furcatum, sp. n. (Tab. XX. figg. 16-19.) 



1. incurvo simillimum. Differt ab illo : elytris concoloribus, venis concoloribus. Femorum spinao omnes 

 nigrse ; coxse saltern intermediae subtus nigrae. Pectus efc pleurae frequenter nigro-varia. 



biol. CENTR.-AMER., Orthopt., December 1898. 3 li 



