WATEE BEEIMS IH KELATION TO PONDFISH CULTUEE. 



273 



margin and not at the apparent end of the appendage; it is also hollow and communicates with a tube 

 that opens into the mouth. Each maxilla is made up of a smaller basal segment and a larger second 

 segment, which has a two-jointed palpus on its tip and a chitinous projection covered with setae at its 

 inner distal comer. The labial palps are one-jointed. 



In the first legs the penultimate segment is prolonged at the inner distal comer, and the projection 

 is toothed along the margin that faces the last joint, against which it shuts, forming a sort of chela. There 

 is but a single terminal claw, with a short basal spine. 



Pupation. — From 20 to 25 days after hatching the larva is ready to pupate. It crawls a long distance 

 from the water's edge and forms its pupal chamber in rather dry mud. Into this it pushes for half an 

 inch or more and there hollows out a spherical chamber about 5 mm. in diameter. It remains inside of 

 this chamber from four to six days before transforming. The jointed spines are all discarded with the 

 larval skin; of course many of them get broken during the formation of the pupal chamber, especially 

 the long, narrow ends where the tracheoles are located. It would seem, therefore, as if the spiracles 

 must begin to function before the transformation takes place. They become visible during this prepupal 

 period, and with the disappearance of the tracheolar spines they assume their proper functions. 



Description of the pupa. — General form an elongated oval, 3.5 mm. long and 1.75 mm. wide. It ia 

 white or sometimes cream-colored, with a decided yellowish tinge, the eyes black or dark brown. The 

 most striking feature is the position of the two front pairs of legs. In these the tibiae and tarsi are in a 

 straight line and are folded tightly against the femur. The three are then turned forward until they 

 stand at an angle of 45° with the body axis, the knees projecting a considerable distance on either side 

 of the head. The anterior margins of the front legs touch the eyes, and the antennae are carried diag- 

 onally across the anterior half of the eyes. Each knee of these two anterior pairs is armed with a stout 

 spine; the head has two short spines between the eyes and one posterior to each eye; the pronotum has 

 10 long, curved, simple styli on its dorsal surface, and a short jointed one on either side of the posterior 

 margin close to the mid line. The meso and meta thorax have four short dorsal spines, two on each 

 segment. Each of the first six abdomen segments has on its dorsal surface four long styli, two lateral 

 and two dorsal, and between the latter a short spine on either side of the mid line. The seventh segment 

 has four shorter styli and the last segment has six. 



The pupa lies on its back more than any of the other pupae studied, but also rests upon its ventral 

 surface, with the body arched strongly upward, like the other pupae. When in this position, it is sup- 

 ported on the spines at the knees of the first two pairs of legs and the styli on the last abdomen segment. 

 Of 16 pupae reared to the adult stage, 12 remained in the pupa stage 12 days and four transformed at the 

 end of the tenth day (fig. 9, p. 272). 



Habits of the adult. — The adults swim slowly and with considerable effort, moving the legs alter- 

 nately as in walking. The tibiae of the first and second pairs of legs and the tarsi of all three pairs have 

 long fringes of swimming hairs. In marked contrast to their labored swimming they walk and run 

 on land with great agility, but can not, or at least do not, jump at all. They fly readily from pond to 

 pond, but apparently can not cover very long distances. They live among the plants in shallow water 

 and are not found in the open parts of the ponds. As far as observed they feed entirely upon Chara 

 and Nitella. 



Description of the adult. — General form elongate-ovate, quite strongly convex; color pale «traw- 

 yellow with black markings; length 3.5 to 4 mm. Head with a large crescentic black spot between 

 the eyes, punctate except in front of the black spot; eyes nearly circular in outline. Pronotum with 

 a pair of basal black spots, rather sparsely punctate. Legs pale yellow except the femora of the third 

 pair, which are dark brown ringed with yellow at their distal ends. Posterior coxae reaching the last seg- 

 ment of the abdomen, punctate. Elytra each with 10 rows of punctures and a partial row between 

 the third and fourth rows, and with seven or eight black spots more or less confluent. 



Genus HALIPLUS Latreille. 



Haliplus (Latreille, 1802, p. 77). 



Another genus of small beetles, which, both in the larval and adult stages, 

 feed exclusively upon algae. They, too, like the members of the preceding genus, 

 are yellowish or reddish in color with black spots on the elytra. They may be 



