274 On Aquatic-Carnivorous Coleoptera or Dytiscide. 
The disposition of the marks on the elytra is quite similar to that existing in 
Canthydrus grammicus (No. 50), but the black marks are broader; the difference 
in the punctuation of the elytra renders the two very distinct. I have seen only 
a single individual, which is probably a male, it has the apical ventral segment, 
flattened or depressed except at the base. 
South California, (Cape St. Lucas). 499. 
49, Canthydrus centralis, n. sp.—Ovalis, sat convexus, pernitidus, testaceus 
prothorace disco infuscato; elytris nigris, vittis tribus testaceis, subseriatim 
punctatis. Long. 3, lat. 1s m.m. 
In this species the black colour on the wing-cases predominates the yellow, so 
that this latter forms three rather narrow longitudinal stripes ; these commence at 
the base, and are there broadest, the internal one becoming gradually more 
indistinct behind, does not reach the extremity, the second is shorter and extends 
but little beyond the middle, the third extends to the apex, and in front sends off 
a branch to the shoulder, which is thus largely yellow; besides these stripes the 
lateral margin in the middle is yellow. Although the surface is very polished, the 
subseriate punctuation of the elytra is very distinct, and on careful examination 
traces may be discovered of an irregular very obsolete punctuation. The sexes 
show little difference except in the tarsi, each having the greater part of the last 
ventral segment a little hollowed. 
Guatemala, (S. Geronimo, 1879, Champion). 1168. 
50. Canthydrus grammicus, n. sp.—Ovalis, latiusculus, sat convexus et elongatus, 
pernitidus, rufo-testaceus; elytris sutura vittisque tribus (externa interrupta) nigris ; 
elytris punctis paucis subseriatis. Long. 32, lat. 2 m.m. 
The sutural vitta extends to the apex, the one next to it nearly to the apex, 
while the middle one is considerably abbreviate, the outer one does not reach the 
shoulder, but there is a short humeral stripe which overlaps it. I have seen only 
four individuals, which are all females, and have the last ventral segment impressed 
on each side so as to make the middle part appear prominent. 
South America; Amazons. 498. 
51. Canthydrus concolor, n. sp.—Oblongo-ovalis, posterius acuminatus, convexus, 
nitidus, fulvus, elytris sparsim inconspicue punctatis. Long. 2%, lat. 13 m.m. 
This species resembles the larger individuals of Hydrocanthus flavus (No. 70) 
exactly, but appears to me to have the posterior tarsi, shorter and thicker. 
Madagascar. 491. 
