COLEOPTERA 243 



Group P TER OS TIC HIDES. 



This is one of the most enormous of the divisions of Carabidae, but in the Hawaiian 

 islands comprises only a small group of closely allied forms. They may be easily 

 recognised by the " fault " in the margins of the elytra (Plate VI. fig. i 2). 



The genera I adopt are ot the simplest kind depending entirely on the thoracic 

 setae. 



No prothoracic seta Metrothorax. 



One prothoracic seta, at hind angle Atelothorax. 



One prothoracic seta, at middle of side Tliriscothora.x. 



Two prothoracic setae, one at hind angle, one at middle Meiydothorax. 



Mecvclothokax, gen. nov. 



Prothorax utrinque setis duabus munitus, una ad angulum posteriorem, altera 

 paulo ante medium lateris sita. Alae vestigiales. 



This genus includes a considerable variety of forms all of which are distinguished 

 by their atrophied wings from the antipodean genus Cyclotliorax, which seems to be the 

 only nearly allied form yet known. 



It is very difficult to tabulate the species, but the following may serve as a key to 

 the arrangement here adopted. 



Small forms with a decidedly transverse, non-cordate thorax (Plate VII. tig. 4), 



which is never furnished with a distinct neck or basal constriction species i — 8. 



Larger, but otherwise as above %'^tc\t% (), M.bradycellinus. 



Small forms, with narrow base to the thorax, and sharp posterior angles ; this 

 group leads by gradations to the group with cordate thorax, but has the 



thorax shorter in proportion to the width species 10 to 14. 



Species with cordate thorax, i.e. a neck, or basal constriction (Plate VII. 



fig. 6) species 15 to 18. 



Larger forms with broad base to thorax and elytra (if the base of thorax is 



narrow, M. pele, montivagus, l>cinbidiciis, there is no neck to it) species 19 to 30. 



{a) sculpture of elytra abnormal, the foveoles being more or less increased 



in number or size species 19 to 22. 



(b) sculpture simple species 23 to 30. 



(i) Alecyclotliorax pitsillns sp. nov. 



Angustus, subparallelus, piceus, antennis pedibusque rufo-testaceis, elytrorum mar- 

 ginibus suturaque rufescentibus, apice testaceo ; thorace fortiter transverse, ante basin 

 hand constricto, basi lata, punctata ; elytris subtilissime striatis, striis subtiliter punctatis, 

 ■ •xterne desinentibus, apicem versus obsoletis. Long. 3^ — 2i\ mm. 



Plate VH. fig. 4. 



The smallest of the group, and readily recognised by the fine very regular series of 

 punctures on the elytra ; of these series there are six, but the outer one is very fine, and 

 much abbreviated, and there is no trace of a seventh ; at the tip only the sutural two can 



