630 On Aquatic Carnivorous Coleoptcra or DijtiscidcB. 



974. Colymbetes substrigatus, n. sp, — Ovalis, eloiigatus, sat convexus, nitldus, 

 nigro-piceus, antennis palpis, capite anterius et in medio verticis thoraceque ad 

 latera rufescentibus, elytris parum conspicue transversim testaceo-undulatis; corpore 

 sublsevigato, elytris obsolete transversim strigosis, versus suturam Isevigatis, })uucti3 

 seriatis conspicuis, abdomine sutura secunda ventrali utrinque prope medium 

 conspicue serratulo. Long. 16, lat. 81 m.m. 



The male has the basal joints of the front and middle tarsi slightly incrassate 

 but greatly compressed, and furnished beneath with four series of rather small 

 round palettes ; there is but little sexual difference of sculpture, the transverse striae 

 are rather less distinct in the male than in the female. The species resembles 

 Dytiscus fuscus, but is rather smaller and darker in colour than the average repre- 

 sentatives of that species, and is very readily distinguished by its obsolete 

 sculpture. 



Arabia. 921. 



975. Colymbetes piceus, Klug, M.C. — Ovalis, sat elongatus et convexus, nitidus, 

 nigro-piceus, antennis palpis capite anterius et in medio verticis thoraceque ad 

 latera rufescentibus, elytris parum conspicue transversim rufo-undulatis ; corpore 

 sublsevigato, elytrorum punctis seriatis conspicuis; abdomine subura secunda 

 ventrali utrinque prope medium conspicue serratulo. Long. 155, lat 8 m.m. 



This species is excessively closely allied to C substrigatus, but is a little smaller 

 and less elongate, and shows scarcely any rudiments of the transverse sculpture of 

 the wing-cases ; it is also a little smaller and less elongate. The male characters 

 seem to be quite the same, the female T have not seen. 



SinaL 922. 



Q7&. Colymbetes vagans, n. sp. — Ovalis, latior, convexus, nitidus, piceus, antennis 

 pedibusque rufis, capite anterius et in medio verticis ferrugineo, prothorace elytrisque 

 lateribus basi nifo-testaceis, his versus latera rufescentibus et transversim nigro- 

 irroratis ; corpore subloevigato, supra subtilissime punctulato, elytris punctis seriatis 

 conspicuis, abdomine sutura secunda ventrali utrinque prope medium evidenter 

 serratulo. Long. 1 5, lat. 8 m.m. 



This species is very closely allied to the preceding, but is distinguished by 

 its broader, shorter form, and its more dilute colour. On the elytra near the sides 

 towards the extremity, there may be detected traces of undulated transverse sculpture, 

 which seems to arise rather from a peculiar arrangement of the very fine punctures, 

 than from the existence of any distinct transverse striae. The hind legs are shorter 

 and stouter than in the allied species. The male characters seem to be nearly the 



