THE FAIRY SHRIMPS (PHYLLOPODA) 671 



36 (i) Body with a well-developed carapace 37 



37 (52) Body depressed, covered dorsally by a depressed shield. 



Suborder Notostraca . . 38 



38 (45) Telson ending in a long, paddle-shaped outgrowth. . Lepidurus . . 39 



39 (40) Telson short, obtusely pointed, spiny on edge. 



Lepidurus glacialis Kroyer 1847. 



An arctic species recorded from Greenland and Labrador. The carapace 

 is very large and regularly ovate; twelve segments are exposed behind it. 



FIG. 1031. Lepidurus glacialis. Telson. X 6. (After Packard.) 



40 (39) Telson spatulate 41 



41 (42) Telson carinate dorsally; carapace large, leaving only five body seg- 



ments and telson uncovered. 



Lepidurus couesii Packard 1875. 



This species occurs in Utah where it frequents "prairie pools of 

 various sizes. 



FIG. 1032. Lepidurus couesii. Telson. X 6. (After Packard.) 



42(41) Telson not carinate dorsally ; -..->... ; : -. ... 43 



43 (44) ~ Telson long bilobed; carapace short, without spinous crest. 



Lepidurus bilobatus Packard 1877. 

 This species has not been recorded since the Hayden survey, when it was taken in Colorado. 



44 (43) Telson long, not carinate, sometimes bilobed; carapace with a median 



spinous crest Lepidurus lemmoni Holmes 1894. 



California. The cercopods are very long in this species. 



45(38) Telson short, cylindrical, simple. . . . . .. . . Apus . . 46 



46 (47) Carapace as long as the portion of the abdomen projecting beyond 



it; telson short with two median and two lateral spines on 

 its dorsal median third. . . . Apus aequalis Packard 1871. 



A widely distributed species occurring in Mexico, Lower California, Texas, 

 Nebraska, and . Kansas. It [has 23 segments exposed behind the carapace. 

 Fig. 1012 shows the form of this species. 



FIG. 1033. Apus aequalis. Telson. X 6, (After Packard.) 



47 (46) Carapace shorter than the portion of the abdomen exposed behind 



it 48 



48 (49) Telson long, with three median and two lateral spines on its dorsal 



median third; 29 segments exposed behind carapace. 



Apus newberryi Packard 1871. 



Recorded from Utah and Colorado. The hairs along the cercopods are 

 said to be remarkably fine. 



FIG. 1034. Apus newberryi. Telson. X 6. (After Packard.) 



49 (48) More than 30 segments exposed behind carapace 50 



