Localities in which Pellagra is Prevalent. 4S 



fringe of hairs. A tuft of similar hairs about the bases of 

 the antennae. Body beneath yellow to reddish, darker at the 

 sutures. Legs reddish yellow. Male, length 11.1; diameter 

 5.5 mm. Female, length 13.4; diameter 6 mm. 



These insects are predatory, both in the larva and adult 

 stages. The young were not seen. Larvae of the genus 

 may be recognized by their elongate slender bodies bearing 

 on each abdominal segment a pair of long lateral plumose 

 respiratory appendages, the posterior somite with four such 

 appendages directed posteriorly. 



Parnidse. 



Perhaps the most characteristic beetles of the waters 

 are members of this family. The adults appear by structure 

 completely unadapted to life in the water, being provided 

 with legs of the type seen in most terrestrial members of 

 the order Coleoptera. They do not swim, but by means of 

 long and strong tarsal claws cling tightly to the under sides 

 of stones and wood, and are there shielded to some extent 

 from the force of the current. Several species were rather 

 common in the streams, and examples are figured. 



The larvae are among the most singular of the immature 

 stages of aquatic insects. The crust of the dorsal side of 

 the body is in them greatly developed, expanded, and the 

 segments closely fitted to each other, producing a convex 

 shield, the edges of which are held close against the under- 

 side of objects in the water. The limbs and head of the 

 insect itself are to be seen only when the larva is detached 

 and turned over. Like the adult it does not swim, but 

 trusts to its capacity to cling tightly, and thus lives and 

 thrives where the water races and tumbles among the rocks. 

 The species are so generally present where Simulium was 

 found that I have thought it worth while to note below the 

 different species collected in the streams, having in mind a 

 possible relation between the two, either as competitors or 

 enemies. 



Dryops lithophilus, Germ. — An elongate moderately con- 

 vex black beetle, of a faint bronzy green color, found 



