DYTISCIDA. » 799° 
A single female in a very bad state of preservation seems to belong to an undescribed 
species; it is allied to the convex members of the genus, such as T. depictus; the 
thorax is apparently not marked with black. 
MEGADYTES (p. 46). 
Megadytes fraternus (p. 47). 
To the localities given, add:—Panama, Volcan de Chiriqui 4000 to 6000 feet, 
Panama city (Champion). 
Megadytes giganteus (p. 47). 
To the Mexican locality given, add:—Presidio (Forrer). 
CYBISTER (p. 47). 
Cybister fimbriolatus (p. 48). 
The specimens from Vera Cruz, alluded to as forming a well-marked variety of short 
form, I now consider to be C. explanatus; the only evidence of the existence of this 
North-American species at Vera Cruz is therefore the unique specimen of a female 
variety also mentioned ((. ¢.). 
1 (a). Cybister explanatus. 
Cybister explanatus, Lec. Aun. Lyc. N. York, v. p. 202’; Sharp, Trans. Roy. Dubl. Soc. n. s. ii 
p. 734’. 
Hab. Norra America, California! 2,—Mexico, Vera Cruz, near the city (Hoge). 
This species is readily distinguished from the shorter varieties of C. fimbriolatus by 
the spinose angle of the hind femora. The only female before me has a well-marked 
sexual sculpture of irregular scratches on the basal part of the wing-cases, covering 
scarcely one fourth of their area; in this respect it differs from the description (which 
states that there is no sexual sculpture on the elytra) of the female of C. explanatus. 
1 (8). Cybister cavicollis. 
Ovalis, convexus, latus, supra olivaceus ; capite, antennis, prothorace elytrisque ad latera testaceis 5 -subtus 
piceus, abdomine dilutiore; pedibus quatuor anterioribus rufis. 
Long. 30, lat. 173 millim. 
Hab. Mexico, near the city (Hoge). 
Although we have received only one female of this insect it is clearly a distinct 
species; it resembles C. explanatus more than any other member of the genus, but is 
readily distinguished therefrom by the hind femora not being spinose at the outer angle; 
this angle is, however, quite acute and even minutely prominent. The upper surface 
has no sexual sculpture, except that on each side of the thorax near the hind angle 
