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sized cupules on long stalks. The basal segment has two rows, one of 15 cupules across the center of the 
segment and another of 20 cupules along the distal margin. The proximal half of the basal joint is 
covered with fine hairs. The second segment has a single row of 21 cupules, and the third segment a 
single row of 20 cupules, both along the distal margins. There is also a band of short hairs on the ventral 
surface of the basal joint of the tarsus of the second legs and three or four coarse folds at the apex of the 
hind coxae. 
Wickham has given a short description (1893, p. 324) of the male tarsus of this species with a figure 
(pi. 5, fig. 2). He also described and figured the male tarsus of Cybister explanatus from California (pi. 
6, fig. 4), and described without a figure that of Cybister tripunctatus, an African species. The obsolete 
claw of the hind tarsus of the female varies much in size. In one specimen it could scarcely be detected; 
in another it was nearly a third as long as the large claw. 
In all the other beetles raised from larvse the adult emerged perfectly formed, except in one 
instance. Of the Cybister adults, however, 75 per cent were malformed in some particular. A front leg 
was lacking in one, a hind leg in another, some of the mouth parts in a third, a fourth had a wry 
neck, and so on. Whether this is true also of those that emerge under natural conditions could not be 
determined. 
Genus DYTISCUS Linnaeus. 
Dytiscus (Linnaeus, 1758, p. 411). 
This is another genus of large beetle, of which both the larvae and the adults 
kill and eat young fish. These beetles are dark, olive-brown in color, with a dull 
yellow stripe along the sides of the thorax and elytra; the front and hind margins 
of the thorax are also usually yellow. The claws are equal in both sexes, and in 
the males the basal joints of the front tarsi are broadly dilated and armed with 
sucking disks of different sizes. 
Dytiscus verticalis Say. Figures 34-38. 
Dytiscus verticalis (Say, 1825, p. 92). 
Eggs. — No direct observations have been made with reference to the eggs of this species, but they 
are probably deposited singly in incisions made by the female with her ovipositor in the stems of water 
plants in a manner similar to that followed by the female of Dytiscus marginalis. 
Habits of the larva. — The material for this species consists of three adults, one of which was taken 
from a pupal chamber, a larval skin from the same chamber, and two larvae nearly full-grown. This 
larva, like that of Cybister, swims more by means of the fringe along the lateral margins of the last two 
abdominal segments than by its legs. The latter are poorly fringed with swimming setae, but make 
up for it in their length. When swimming slowly, the legs are used alone, but in rapid locomotion the 
whole body contributes. This larva also can jump to a considerable distance by sudden flexure of the 
last two abdominal segments, and it can do this on land as well as in the water. According to Brocher 
(1913, p. 125) when the Dytiscus larva breathes it may either stand upon some sort of vegetation and 
reach upward, thrusting the tip of its abdomen above the surface of the water, or, releasing its hold on 
the vegetation, it may float slowly upward, the abdomen preceding, until the tip of the latter reaches 
the surface; or, when the specific gravity of the body is greater than that of water, it may swim with its 
head directed upward and on reaching the surface turn parallel to the latter and thrust its abdomen 
above the surface. In all three cases the cerci are turned down against the surface film, this action both 
opening the posterior spiracles and supporting the larva while it breathes. 
With reference to food we find the following statements, which were made not of this particular 
species but of the genus in general. Evermann and Clark (1920, Vol. I, p. 639) stated that the larvae 
of Dytiscus attack the tadpoles of the leopard frog and devour them. Dytiscus larvae were found by 
Needham and Williamson (1907, p. 485) in the “Gym” pond on the campus at Lake Forest, 111., feeding 
upon Corethra pupae. Wright (1920, p. 42) stated: “The water beetles, especially their larvae (water 
tigers) and dragonfly nymphs also take their heavy toll of tadpole lives.” Miall (1895, p. 47) made 
the statement: “Almost all kinds of aquatic animals, snails, worms, insects, tadpoles, and fishes are 
devoured by the insatiable Dytiscus larvae.” Garman (1890, p. 163) testified: “Both adults and young 
lead a predatory life, attacking and devouring whatever they can master. They do not hesitate to attack 
animals many times larger than themselves and are very destructive in fishponds to young fishes. They 
are in turn eaten by the larger fishes.” 
