328 



BUULETIl^ OF THE BUREAU OF FISHERIES. 



Comstock in Manual of the Study of Insects (1912, p. 527, fig. 636) gave a picture of one of these 

 cases. Jlef erring to it in the text he stated: "Some species deposit as many as a hundred eggs in one 

 of these waterproof packages (fig. 636)." The cases are waterproof only in the sense that water does 

 not injure them and not in the sense that water can not enter them, since they are left open to allow 

 the exit of the larvae. Again, the large floating cases of Hydrous and not the one figured by Comstock 

 are the ones that contain 100 eggs. 



Description of the newly hatched larva. — Length 4.5 mm., and width of the thorax 0.8 Am.; color 

 light brown. Head trapezoidal, about the same length and width, slightly narrowed posteriorly; fronto- 

 clypeal sutures indistinct; frontal sutures straight, converging and uniting to form an epicranial suture 

 less than one-twelfth of their own length. Frons flat and broadly triangular, the three sides of the 

 triangle about equal. Anterior margin of head somewhat concave, the lateral expansions of the epis- 

 toma projecting in front of the labro-clypeus. The teeth of the latter are large and include a conical 

 tooth at the center larger than any of the others and, on either side of it, two smaller teeth close together 

 and a larger one removed a little distance. The sinuses on either side of the central tooth, between 

 the two teeth and the distant one, and on the outside of the latter, each carry a short and stout spine. 

 The frontal margin of the epistoma has no spines except two at each outer comer, side by side, about 

 the same size as those on the labro-clypeus. Near the anterior margin of the frons is a transverse row 

 of four small setae nearly in a straight line; a fourth of the distance behind them are two more, one on 

 either side of the mid line. There is a seta outside the sixth eye, another outside the fifth eye, and a 

 row of three behind the ocular area. The first (anteiior) eye is only a little larger than any of the others. 



The basal joint of the antenna is only a third longer than the other two joints together, but the 

 terminal joint projects beyond the tips of the mandibles. The -fingerlike appendage on this joint is 

 apparently two-segmented. These antennae are much stouter than those of the lateralis larva, espe- 

 cially the second and third joints. The mandibles are the stoutest and most strongly curved of the 

 three species here described, and their tips are comparatively blunt. The distal tooth on the inner 

 margin is also stouter, its bifid tip is more bluntly rounded, and the teeth on its inner margin are shorter 

 and coarser. The middle tooth on the left mandible is broadly triangular and not double but stands 

 apparently in the center of the groove. The proximal tooth is minute and on the ventral margin of the 

 groove, but its proximal edge runs across the groove nearly to the dorsal margin. On the right man- 

 dible there are two small proximal teeth, side by side, one on either margin of the groove. The maxillae 

 are stouter than those of lateralis but otherwise similar to them. The labium is also stout and shorter 

 than in lateralis, the tips of its palps reaching just beyond the center of the maxillary stipes. The 

 mentum has convex sides, and its anterior comers are produced into blunt spines; the ligula is cyHn- 

 drical and only slightly tapered; the terminal joint of the palDus is four times the length of the basal 

 joint. , 



The mature larva. — When fully grown the larva is 12 to 15 mm. long and 3 to 4 mm. wide. This larva 

 is very similar to that of lateralis but is somewhat larger, darker in color, and more densely clothed with 

 hairs. The papillae on the abdomen are longer, more numerous, and carry larger tufts of hairs; the 

 mandibles are stouter, shorter, and not as acuminate; th^ maxillae are shorter and stouter, and the upper 

 lip of the stigmatic atrium is evenly rounded instead of being cut into narrow lobes. Figure 130 shows 

 the upper surface of the head of a mature lateralis larva, while that of the mature glaber larva is shown in 

 Figure 137, and the two larvae can be distinguished by the color patterns. The yellow on the dorsal 

 surface of the head and the five yellow stripes on the ventral surface are much more pronoimced in 

 the present species. Sometimes this larva has a brown streak through the head along the mid line 

 of the dorsal surface, but even then the color pattern is distinctly visible. This larva, like the pre- 

 ceding species, undergoes changes with age; the antennae and maxillae become more slender, and 

 their basal joints increase in relative length. The mandibles are less acuminate, but the proximal 

 teeth on their inner margins remain broader, blunter, and closer to the distal teeth than in the lateralis 

 larva. The labium broadens, and the mentum acquires a formidable set of short spines on its dorsal 

 surface. When fully matured, the larva becomes almost black and is densely covered with papillae 

 and hairs. 



The habits and food are the same as those of the lateralis larva; Richmond (1920, p. 35) said that 

 the glaher larvae he reared in an aquarium "fed readily on entomostracans and small tadpoles." 



Description of the pupa. — The pupa is like that of the preceding species, with the following differ- 

 ences. It is slightly longer (9.5 mm.) but no wider* the labrum and the distance between the eyes 



