708 On Aquatic Carnivorous Colecptcra or DytiscidcB. 



varieties may prove to be good species ; the sexual characters of male and female 

 distinguish it amply from the following ones. 



In Mexico the females appear to be usually nearly or quite destitute of sexual 

 sculpture. 



South America to Mexico ; Bahia (Castlenau) ; Santa Cruz, 10 to 17, 10, 1872, Van Volxem ; Panama, 

 Cliontales, Mexico. 1103. 



1107. Megadytes fraternus, n. sp. — Ovalis, satlatus et convexus, anterius angus- 

 tatus, capite anterius prothoraceque ad latera anguste testaceis, elytris versus 

 apicem obsolete ferrugineo-maculatis, subtus nigricans pedibus quatuor anterioribus 

 rufis, tarsis intermediis picescentibus, pedibus posterioribus nigro-piceis ; antennis 

 gracilioribus. Long. 22j, lat. 13 m.m. 



The front tarsi of the male are large, attaining nearly 3 m.m. in the transverse 

 direction, their claws are elongate, the front one being conspicuously longer than 

 the other ; on the undersurface the palettes are broad, the basal fringing hairs are 

 stout and elongate, and at the heel diverge distinctly but not greatly from the 

 palettes ; the pubescent area has a great extension in the transverse in comparison 

 with the longitudinal direction. The intermediate tarsi bear elongate sexual 

 pubescence on the three basal joints. The female has the thorax more dull than 

 the male, and the elytra show a highly developed and beautiful sexual sculpture, 

 consisting of very short but regular rectilinear impressions covering the whole 

 surface, except on a quite small space at the apex. 



This species is variable, or rather perhaps will prove to be one of several closely 

 allied species ; what I have decided to treat as varieties being in that case really 

 distinct species. 



In Guadeloupe and St. Domingo the sculpture in the females does not reach 

 quite to tbe lateral margin. In Surinam and Demerara a very large variety occurs, 

 with the male tarsi very highly developed. The type above described by me is 

 from Panama ; and in the more southern parts of South America the sexual 

 characters appear to be not quite so highly developed. 



Panama; Guatemala (Duenas, G. C. Cliampion), Guadeloupe, St. Domingo, Demerara. 1104. 



1108. Megadytes steinheili, Wehnoke {rx parte) Stet. Ent. Zeit. xxxvii, p. 359. — 

 Ovalis, latiusculus, anterius minus angustatus, capite anterius prothoraceque ad 

 latera anguste testaceis, elytris versus apicem obsolete ferrugineo-maculatis ; subtus 

 nigricans, pedibus quatuor anterioribus rufis, tarsis intermediis picesentibus, pedibus 

 posterioribus nigro-piceis ; antennis gracilioribus. Long. 23, lat. ISi m.m. 



This species is very closely allied to M. fraternus, but is bi'oader in front, and the 

 sexual characters are even more highly developed, and the shape of the male tarsi 



