320 GEOLOGICAL SURVEY OF THE TERRITORIES. 



Apus ^qualis Packard. 



Plates XV, figs. 1, la, U; XVIII, fig. 1; XIX, fig. 2; XX, fig. 2. 

 Apus ccqualis Packard, Amer. Jonru. 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. longicaudatus. There are 17 teeth on each side of the sinus of the 

 carapace. Eyes considerably larger than in A. longicaudatua ; 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 the same form as in A. netcherryi, while 

 the gill is smaller and more regular in form. In the tenth jDair of feet 

 the four endites are rather longer and narrower than in A. netcherryi; 

 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 setse, 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 sjiiues 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, 9"^"'; 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, 5.8™™; length of abdomen be- 

 hind the carapace, 14™™; length of caudal appendages, 19™™. "Mat- 

 amoras, Mexico, General Couch," "Kansas, No. 5," Mus. Chicago Acad. 

 Sc, "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 Dug^s, September, 1877, of an Apus col- 

 lected at Guanajuato, Mexico, I am inclined to refer it to A. ccqualis, 

 though in comparing the drawing with the specimens from Matamoras 

 the antennae are represented as much too short, and the body behind 

 the carapace too thick ; but it fairly represents the proportions of the 

 carapace. 



1 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 



