744 Oil Aquatic Carnivorous Coleoptera or Dytiscidce. 



The male has the front tarsi large, attaining 4 m.m. in the transverse direction ; 

 the two basal joints of the intermediate feet are entirely clothed beneath with short 

 sexual pubescence. The female has a highly developed sexual sculpture, the thorax 

 being entirely covered with short irregular scratches, and the elytra having elongate 

 scratches on all but about the hinder one-sixth of their surface, the scratches how- 

 ever do not quite attain the suture except at the base ; the epipleurae are flattened 

 and obliquely horizontal, the torsion commencing near the base and ceasing gradually 

 about the hind margin of the second ventral segment. 



The variegation of the antral segments is in this species indefinite, the first and 

 second ones are largel}' pale towards the sides, while the yellow lateral colour on 

 the following segments assumes more the form of indefinite yellow spots. 



The locality of this species is open to some little doubt. I have a pair from 

 W. W. Saunders' collection, labelled " bengalensis, Aube," but with no locality ; 

 another specimen stood in Dejean's collection labelled "Dytiscus javanus, mihi h. in 

 Ins. Java ;" a fourth individual stood in Chevrolat's collection as one of three in- 

 dividuals under the label "Cybister ]imbatu&,Fab. Dj. Aube, aciculatus Olivier, India 

 or. ex Mus. olivieri ;" the other two individuals were females of Dytiscus limbatus. 



India (?) (Java?). 1095. 



11(55. Cybister cognatus, n. sp. — Major, ovalis, supra olivaceus, capite anterius 

 prothoraceque ad latera testaceis, elytris vitta intramarginali, versus apicem argute 

 harnato-dilatata, testacea ; corpore subtus variegato, prosterno pectoreque in medio 

 nigricantibus, abdomine in medio late fuscescente, lateribus late vageque testaceis ; 

 pedibus anterioribus et intermediis testaceis, his tarsis piceis, pedibus posterioribus 

 nigricantibus femoribus ad apicem rufis. Long. 35, lat. 193 m.m. 



The male tarsi are only moderately large attaining about 3 m.m. in the transverse 

 direction; on the intermediate feet the patches of short sexual pubescence on the 

 first and second joints seem to be a good deal smaller than in the allies, the one on 

 the second joint being quite narrow. 



The sexual sculpture of the female is but moderately developed, being obsolete 

 on the thorax, and on the elytra extending only about half way to the apex, and 

 being broadly absent along the sutural region ; the epipleurae are only slightly and 

 obscurely flattened, and the torsion extends but for a small distance in the longi- 

 tudinal direction. 



This species bears an extreme resemblance on the upper side to Dytiscus limbatus 

 (No. 1157) but is readily distinguished by the colour of the undersurface : it is allied 

 to the preceding species, but is distinguished readily enough, the form being less 

 narrow in front, and less convex, the dark colour on the undersurface is less exten- 

 sive, and the male tarsi are different, and the sexual distinctions in the female much 

 feebler. The two species differ moreover remarkably from all their allies by the 

 highly developed and remarkable structure of the oedeagus. 



