712 On Aquatic Carnivorous Coleoptera or DytiscidcB 



1115. Megadytes gravidus, n. sp. — Ovalis, iatus, anterius angustatus, sat con- 

 vexus, supra olivaceo-niger, capite anterius prothoraceque ad latera testaceis, elytris 

 vitta intramargiuali obsoletissima, fere tantum ad basin distinguenda ; subtus niger, 

 pedibus quatuor anterioribus rufis, tarsis intermediis piceis ; pedibus posterioribus 

 piceis, tibiis superue rufescentibas, femoribus nigris ; elytrorum epipleuris sat latis. 

 Long. 33, lat. 19b m.m. 



I am acquainted only with the female of this species, which shows no trace of 

 any sexual sculpture. 



The species is probably very closely allied to those preceding, especially to C. 

 robustus, but the very obsolete lateral band of the elytra if constant, wiU render it 

 easily distinguishable. 



Brazil. (Santa Cruz, Van Volxem). 1111. 



1116. Cybister costalis, Aube, Troyus costalis, M. C. -Ovalis, Iatus, supra olivaceo- 

 niger, capite anterius prothoraceque ad latera testaceis, elytris lateribus ante 

 apicem sub-explanatis, vitta intramarginali, posterius lata sed parum determinata, 

 testacea ; subtus niger, epipleuris latioribus, pedibus anterioribus rufis, femoribus 

 in medio nigricantibus, intermediis piceis, femoribus rufescentibus medio nigri- 

 cantibus, posterioribus nigro-piceis, tibiis superne plus minusve rufescentibus. Long. 

 31, lat. 19 m.m. 



The male has the front tarsi moderately large attaining 3 m. m. in the transverse 

 direction ; the intermediate feet have the tliree basal joints furnished with 

 elongate sexual pubescence, and their claws elongate and unequal, the outer one 

 being conspicuously thickened, and its under edge nearly straight. 



The female has a highly developed sexual sculpture, the thorax being entirely 

 covered with deep irregular scratches, and the elytra bearing similar scratches on 

 the greater part of the surface, the sutural portion, however, remains smo.ih 

 except at the base, and the explanate lateral portion is also smooth. 



In the Stet. Ent. Zeit. 1847, p. 52, will be found a long discussion ou Fabricius' 

 species of this name ; the discussion being based on an examination of the Fabrician 

 types in the collections at Kiel and Copenhagen ; the conclusion arrived at is that 

 Dytiscus costalis, lab., is not Cybister costalis, Aube. Schaum's discussion, however, 

 was imperfect, inasmuch as he seems to have been unaware that the earliest 

 descrijition of Dytiscus costalis is contained in the Systema Entemologiae, p. 230. 

 (1775), not in Ent. Syst. I, p. 187, which dates only from 1792. If reference be 

 made to the earlier description, it \s ill be found that it agrees sufficiently with 

 Aube's Cybister costalis to have justified Aube inciting it. On the other hand, it 

 would be improper to assign the name Dytiscus costalis, Fab., to Cybister dejeani, 

 Aube, as is suggested by Schaum on the authority of the type, for Fabricius says, 

 " habitat Surinami, D. Yeats," while C. dejeani is found only in the East Indies. 



