24 FAUNA HAWAIIENSIS 



outwardly with a small curved process. In Thawnatogrylliis this cavity is very deep 

 and abrupt and apparently extends beneath the pronotum, which with the tegmina 

 entirely conceals it. Instead of the two minute orifices there appears to be a large 

 transverse slit, with a small hard spine at either extremity. As in Leptogrylhis these 

 structures are peculiar to the ^. 



All the species of this group are entirely nocturnal in their activities. In the 

 day-time they conceal themselves beneath the bark of trees, in hollow stems, or 

 amongst dead leaves attached to trees, but we have never met with any species that 

 is not arboreal in its habits. All the species of Prognathogryllus, Nesogryllus and 

 Aphonogryllus are extremely rare insects, while the Thaiimatogryllus and several of 

 the species of Leptogrylhis have been taken in some numbers, but even these are 

 rarely or never to be found unless a special search be made for them. 



The genera of Prognathogryllides may be tabulated as follows : 



1. {2) Cerci tribus articulis tarsorum posticorum conjunctis multo longiores Prognathogryllus. 



2. (/) Cerci tribus articulis tarsorum posticorum haud longiores. 



3. {&) Spinae tibiarum posticarum internae externis evidenter longiores. (Tegmina 



aut longa aut nulla.) 



4. (j) $ tegmina nulla Aphonogryllus. 



5. {4) i tegmina longa .., Nesogryllus. 



6. (j) Spinae tibiarum posticarum internae externis haud evidenter longiores. 



(Tegmina squamiformia, saepe minutissima.) 



7. (t?) Metatarsus anterior longissimus : calcar tibiarum posticarum externum et 



superius longum Thautnatogryllus. 



8. (7) Metatarsus anterior minus longus, tantum bis terve longior quam latior : 



calcar tibiarum posticarum externum et superius breve Leptogrylhis. 



Prognathogryllus (sensu strictiori). 



Prognathogryllus Brunner P. Z. S. 1895, p. 896. 



Tegmina abbreviata, vel fere ad apicem abdominis extensa. Alae sat distinctae, 

 ad apices tegminum extensae, vel, si haec longa, his multo breviores. Tibiae anticae 

 tympano instructae ; tibiae posticae spinis utrinque armatae, internis, quam externae, 

 multo longioribus. Cerci ovipositori subaequales. %. 



(i) Prognathogryllus alattts Brunn. 



Prognathogryllus alatus Brunner P. Z.S. (1895) p. 896. 

 (Plate II. figs. 8, 8«, & 8(5.) 



