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BULLETIN OF THE BUREAU OF FISHERIES. 
strongly bronzed; beneath black very shining; abdomen tinged with brown; legs brownish-yellow. 
Elytra of the male feebly sinuate both on the lateral margins and near the tips, the latter separated but 
little and the angles only slightly produced backwards. In the female both sinuations are more pro- 
nounced, the tips are more widely separated, and the angles are more distinctly produced. 
The antennae are peculiar and are very similar to those of Gyrinus, which are usually cited by 
authors as the type of what is known as the irregular form. Each antenna is made up of two parts, a 
proximal portion of three joints and a distal portion of seven joints. The second proximal joint is 
produced into a wide wing, which curves up around the base of the distal portion of the antenna. To 
the inside of this wing is attached the third proximal joint, and the first distal joint is fastened by a 
minute neck to the dorsal surface of this third joint. The distal portion of the antenna is club-shaped 
and six-jointed, the first joint apparently made up of three joints fused. Miall (1895, p. 34) said: “The 
peculiar form of the Gyrinus antenna is probably a means of keeping it dry.” In this antenna the 
enveloping wing of the second proximal joint and the long fringes of hairs on the third joint assist in 
keeping the sensory terminal portion dry. 
The mandibles are large and strong but are blunt and approach the herbivorous type more closely 
than the carnivorous. The maxillae are sharp and sickle-shaped and typically carnivorous; the palp 
is five-jointed and somewhat club-shaped. The labium is well developed, with large circular para- 
glossae and three- jointed palps. 
The fore legs are prehensile, and in the male the tarsal joints are slightly dilated and their ventral 
surface is covered with rows of suckers that stand out like the pile on velvet. Each sucker is a narrow 
tube enlarged at the tip into a cup-shaped disk. 
Genus GYRINUS Geoffroy. 
Gyrinus (Linnaeus, 1758, p. 412). 
Gyrinus (Geoffroy, 1762, p. 193). 
This is a genus whose species are smaller, narrower, and more convex than 
those of the preceding genus. Each elytron has 11 rows of distinct punctures and 
when held so as to reflect the light usually shows a yellowish tint. The legs vary 
from yellow to reddish-brown in color and are relatively longer than in the genus 
Dineutes. The species vary so little that they are hard to distinguish; four have 
been reported from the fishponds but are not found there regularly. They seem 
rather to be itinerant visitors from the river and occur most frequently on the 
ponds that are nearest the river. 
Gyrinus ventralis Kirby, 1837, p. 80. 
Gyrinus limbatus Say, 1825, p. 109. 
Neither of these species breeds in the Fairport fishponds, but the adults are 
occasionally found there in considerable numbers, and hence the more important 
facts in their life History will be of interest. These facts are taken from various 
authors and apply equally to the two species. 
Eggs . — The eggs are laid in rows on the leaves or stems of water plants and closely resemble those 
of the preceding genus in shape, in color, and in time of hatching. 
Habits of the larva . — It swims and breathes in the same manner as the larva of Dineutes already 
described. According to Miall (1895, p. 39) : “ The Gyrinus larva feeds upon water insects and possibly 
upon other aquatic animals. Failing these it will eat the tender parts of submerged plants.” Accord- 
ing to Needham the larvae also “feed upon the body fluids of bloodworms and other small animal prey ” 
(1916, p. 221). It is difficult to understand how a larva like this, whose mouth parts are typically 
carnivorous, and whose mandibles are suctorial like those of the Dytiscidse, can eat vegetable food as 
stated by Miall. 
Description of the larva . — This larva is similar to that of Dineutes, except that the first two pairs 
of lateral gills are fringed with hairs like the other pairs. This larva is only about 14 mm , in length 
and is widest through the second thoracic segment, which is nearly 2 mm. in width. The abdomen 
