LUCY WRIGHT SMITH 
439 
plate a small fleshy lobe attached to the ventral surface of the 
tenth tergite (figs. 20 and 21 Sup. A. P.), sub-anal plates large, 
triangular (figs. 20 and 21 Sul). A. P.). 
Tufts of filamentous tracheal gills groujied about the legs on 
the ventral side of the thorax, and beneath the abdomen; anterior 
to the front legs, three pairs of gills arranged transversely, en- 
circling the neck like a collar, posterior to the same legs, foui 
pairs; posterior to the middle legs, three pairs; posterior to the 
last pair of legs, three pairs, one on the metathorax and one pair 
on each of the first two abdominal segments (fig 27). 
Biology and Morphology 
1840. Gosse, Canadian Naturalist: 231, 2.32. 
1844. Newport, Ann. Nat. Hist., 13: 21 to 25. 
1851. Newport, Trans. Linn. Soc. London, 20: 433 to 4.52. 
1873. Gerstaecker, Zur Morphologie die Orthoptera amphibiotica, pp. 60 
to 74. 
1877. Hagen, Stett. Ent. Zeit., 38: 477 to 489. 
1883. Packard, Third Kept. U. S. Ent. Com., pp. 322 to 325. 
Biological Notes 
Adult. The genus Pteronarcys has attracted attention since 
1844 when Newport discovered that the adult retained, in a more 
or less imperfect state, the tracheal gills of the nymph. Some of 
the early naturalists considered Pteronarcys a nocturnal insect. 
Barnston saw Pt. regalis abroad only at dewfall, or in the night, 
and he observed it “constantly dipping to the surface of the 
water.” Doubleday captured it chiefly “on wet evenings,” by 
day he saw it hidden in crevices of rocks that were constantly 
wetted by the spray of falling water or under rocks, and in other 
damp places. Gosse found Pt. proteus at the Alagog River in 
great numbers hanging to the rocky sides wet by the spray from 
the water-fall, or concealed in crevices of the rocks. 
Newport interpreted this nocturnal habit as evidence of aquatic 
respiration in the adult. He says, 
“They shun the open day, during which they remain secluded 
beneath stones or in damp places, where the air is charged with 
moisture. They come abroad at night, and are constantly in the 
neighborhood of streams and rivers, in which localities also the 
air is saturated with moisture. Under either of these circum- 
stances the branchiae may be sufficient for all purposes of aera- 
tion.” 
TRANS. AM. ENT. SOC., XLIII. 
