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BC) GEOLOGICAL SURVEY OF THE TERRITORIES. 
APUS AQUALIS Packard. 
Plates XV, figs. 1, la, 16; XVIII, fig. 1; XIX, fig. 2; XX, fig. 2. 
Apus equalis Packard, Amer. Journ. Sc. Aug. 1871. 
Two males.—This species differs from the following species in the 
carapace being as long as the abdominal portion beyond it. The dou- 
blure is shorter than usual; while the hypostoma is rather larger, being 
as long as the doublure; the front of the head beneath resembling that 
of A. long gicaudatus. There are 17 teeth on each side of the sinus of the 
carapace. Eyes considerably larger than in A. longicaudatus ; the post- 
ocular tubercle much smaller than in the species just named. In the 
first pair of feet the fifth endite is rather longer than in A. newberryi, 
the fourth longer and slenderer, and the second also long and slender. 
In the second pair of feet the four endites are rather short and broad, 
especially the first; the “scale” (or sixth endite) is much shorter than 
the fifth endite, the latter being long and slender, and in one specimen 
reaching to the base of the telson. The fourth endite in one specimen 
is two-thirds as long as the fifth, in another scarcely half as long. The 
flabellum is smaller, but of nearly thersame form as in A. newberryi, while 
the gill is smailer and more regular in form. In the tenth pair of feet 
the four endites are rather longer and narrower than in A. newberryi ; 
the tips of the fifth endite and its scale are of equal length, the end of 
the latter terminating in a curved spine; the flabellum is much rounded, 
with a long fringe of hair-like seta, but is not much larger than the 
gill itself; telson about as long as in A. longicaudatus, unusually 
smooth, with five median spines, three arranged in a triangle near the 
edge, with two moderately prominent lateral ones at the base of the. 
caudal appendages, the latter moderately spiny, the spines being fine 
and numerous; beneath the telson is quite smooth, with fine spines in 
the middle and on the sides. Number of segments beyond hind edge 
of carapace, 23; beyond last pair of appendages, 11. Total length of 
the body, 29™™; length of carapace, 14™™; breadth, 12.5™™; length of 
carina of carapace, gum , distance from front end of keel to front edge 
of head, 5.2™™; ; length of caudal appendages, 19™™. 
Thirteen females. —Carapace with 20 spines on each side of the 
hinder edge or sinus. The fifth endite of the first pair of feet reaches 
in all the ‘Matamoras specimens but one to the base of the telson, in the 
others midway between the hind angle of the carapace and the base of 
the telson. Number of segments beyond the hind edge of shield, 25; 
number beyond last pair of appendages, 9. Total length of the body, 
29™™; of carapace, 14%™; breadth, 11.5™™; length of keel, 8.5™™; length 
from end of carina to front edge of head, "5. gm. length of abdomen be- 
hind the carapace, 14™™; length of caudal appendages, 19mm. *Mat- 
amoras, Mexico, General ‘Couch, ” « Kansas, No. 5,” Mus. ‘Chicago Acad. 
Se., ‘Plains of Rocky Mountains, No. 390, ” Museum of Yale “College. 
Having been favored by Professor Baird with the opportunity of ex- 
amining a colored painting by Dugés, September, 1877, of an Apus col- 
Jected at Guanajuato, Mexico, I am inclined to refer it to A. cequalis, 
though in comparing the drawing with the specimens from Matamoras 
the antenne are represented as ‘much too short, and the body behind 
the carapace too thick; but it fairly represents ‘the proportions of the 
carapace. 
I have received small specimens of this species from Bosque County, 
Texas, through Mr. Belfrage. One of them was a young one, whose 
total length was 29™™, the carapace along the median line measuring 
