246 BULLETIN OF THE BUREAU OF FISHERIES. 
caudal gills are small and scattering. The ground color is white, covered with a complicated pattern of 
light russet brown; last four abdominal segments, legs, and caudal gills nearly all brown, with narrow 
stripes of white; respiratory trachee bright golden yellow. 
The Mask.—Mentum one-half wider than long, with slightly convex sides; distal margin nearly 
three times the proximal; no lateral sete, one marginal seta near the distal end, one mental seta; distal 
margin smooth. Lateral lobe three-fourths longer than wide; no sete on the outer margin; raptorial 
seta just reaching the tip of the movable hook, the latter long and stout; a minute accessory spine out: 
side the base of each raptorial seta; distal margin deeply toothed, inner tooth cultriform. 
61 
Fics. 61 to 63.—Development of Enallagma signatum: 61, egg; 62, mask of newly hatched nymph; 63, newly hatched nymph. 
GENERAL CONCLUSIONS. 
1. Odonate nymphs feed upon small mollusks, insect larve (including smaller 
nymphs), pupz and adults, entomostraca and larger crustacea, and alge. Some of 
their food, such as Chironomid larve, mayfiy larve, entomostraca, etc., is the same 
as that of young fish, but they also eat the larve or adults of many animals that are 
directly harmful to small fishes, such as diving beetles, water boatmen, crayfish, and 
Cypris. 
2. A few of the largest species may sometimes eat a small fish under natural con- 
ditions, but this is apparently due to stress of hunger and the lack of other food. War- 
ren has proved (p. 206) once for all that the diet of a nymph in captivity furnishes no 
criterion whatever as to its natural food. Careful observations under natural condi- 
tions show that even an Anax nymph need not be regarded as a menace to fish culture, 
but that it may become actually beneficial. 
3. Odonate nymphs furnish one of the very best foods for fishes; the small species 
and the young of the larger species are freely eaten by the fingerlings of practically all 
