28 



BULLETIN OF THE BUREAU OF FISHERIES. 



and curving upward and backward. These two processes and the dorsal lobe 

 of the seventh joint are tipped with tufts of long, coarse hairs. The ninth segment 

 is flattened into a lamina with rounded angles, which is curved upward and back- 

 ward, like the processes on the preceding joints, and has a 

 fringe of short hairs. The surfaces of these last four joints are 

 uniformly covered with a pile of short hairs that can not be 

 wetted by water (fig. 19). According to Miall (1895, p. 81) : 



The antennae are used only for breathing by the submerged insect. Their 

 place as feelers is supplied by the long and forward-directed maxillary palps. 



MOUTH PARTS. 



The mandibles are fully as powerful in the adult as in the 

 larva. Each consists of a single chitin sclerite, curved into a 

 clawlike tip, which is bifid and armed on the inner side with three 

 long and stout teeth; the distal tooth is tripartite at the tip, the. 

 other two are bipartite (fig. 20) . 



Each maxilla is made up of two basal pieces and three outer 

 parts with their subdivisions. The portion that joins the head, 

 the cardo, is somewhat trapezoidal, narrowed and emarginate, 

 proximally, widened and armed with a fringe of hairs distally. 

 •Right antenna The stipes is jointed to the cardo almost in a straight line and 

 serves as a support for the outer parts. The palpifer at the dis- 

 tal end of the stipes is short and cylindrical; the maxillary palp attached to it is 

 four-jointed, slender, and cylindrical, the terminal joint shorter than the second 

 and third joints and neither enlarged nor flattened. To the outer margin of the 



Fig. 19. 



of adult beetle. 



Fig. 20.— Ventral view 

 of mandible of adult 

 beetle. 



Fig. 21. — Ventral view of right maxilla of 

 adult beetle, ca, cardo; dg, digitus; 

 ga, galea; I, lacinia; mxp, maxillary palp; 

 pa, palpifer; st, stipes; sg, subgalea. 



stipes is attached the subgalea, which is deeply emarginate at its proximal end, 

 while at its distal end is hinged the two-jointed galea, each joint about the same 

 length and width. The lacinia on the outer margin of the subgalea is heavily 

 fringed with hairs and carries a long fingerlike digitus (fig. 21). 



