PACKARD.] PHYLLOPODS OF NOETH AMERICA. 317 



two species ; the fringe of hairs is very long ; the gill itself is narrower 

 than in L. couesii or Mlohatus. Iq the tenth pair of limbs the third and 

 fourth endites are mnch longer and narrower than in L. couesii, the gill 

 and flabelhim very different from the other two species, the gill being 

 small, pyriform, with a constriction near the end, while the flabellum is 

 nearly as broad as long, rounded anteriorly, and with the posterior edge 

 straight. 



In the eleventh pair of limbs, bearing the ovisacs, the endites are 

 also longer and narrower than in L. couesii. 



Length of body, 14™"'; of carapace, 10™™; breadth of carapace, 9™™. 



Length of cercopoda, 6™™; of telson, IJ™™. 



Locality. — Eeceived from Southern Greenland, through Dr. 0. F. Liitr 

 ken ; Jacohshavn, North Greenland (Gerstaecker, 1064) ; Cape Krusen- 

 stern, Arctic America (Richardson). 



Lepidurlts couesii Packard. 



Plates XV, figs. 2, 2a; XVII, figs. 2, 3, 7; XXI, figs. 4, 5, 6, 9, 11. 



Lepiduriis couesii Pack. American Naturalist, ix, 311, 1875. Bull. U. S. Geol. and 

 Geogr. Survey, F. V. Hayden, in charge, iii, No. 1, 177, fig. 16. April 9, 1877. 



Compared with Lepidurus productus Bosc of Europe, the carapace is 

 of the same proportions, being large, broad, and leaving above five en- 

 tire terminal abdominal segments exposed, including the telson. The 

 deuticulations on the hinder edge of the carapace are finer than in the 

 European species, and show a tendency to become obsolete on the lower 

 part of the incision. The eyes are slightly fuller, more prominent than 

 in L. py^oductus, and the interocular tubercle is smaller. The mandib 

 ular area of the carapace is the same as in L. productus. Labrum_ a little 

 smaller than in L. productus. The leet are the same as in L. productus. 

 The mandibles in this species (PL XXI, fig. 11) have, on the cutting- 

 edge, six well marked teeth, which are rather blunter, less at.'enuated 

 at the end than in Apus lucasanus (fig. 12). The maxilla (PI. XXI, fig. 

 9) has a three-toothed lobe externally, and the inner larger lobe is- setose 

 throughout. There are usually from ten to twelve spines on the penulti- 

 mate segment, as in L. productus. The chief distinction lies in the very 

 long spatulate telson, which is about twice as long in proportion as that 

 of L. productus, and is long and narrow, varying somewhat in width, and 

 in size. The median ridge and edge are finely spinulose, the tip is well 

 rounded; caudal stylets nearly as long as in L. productus. 



The eggs of this species, PL XXI, are somewhat larger than those of 

 Apus hicasanus (PL X VIII, fig. 5 ; the figures of the ovisacs containing 

 them having been drawn to the same scale by the camera lucida). 



From L. glacialis Kroyer, of Greenland, it diifers in the longer, larger 

 carapace, eleven terminal segments being uncovered in L. glacialis. 

 The sjiines on the excavation are much smaller; telson twice as long, 

 and not sub triangular, and excavated at tip, as in L. glacialis; eyes 

 larger; interocular tubercle decidedly smaller; labrum smaller. The 

 first pair of legs are much longer than in L. glacialis^ in which the endites 

 are very short. 



Length of an average specimen from head to end of telson, 20.2™™; 

 telson, 5™™; stylets, 15-19™"^, 



This species was collected by Dr. Elliott Coues, naturalist of the 

 United States Xorthern Boundary Commission. He writes me that they 

 "occurred in myriads in several small prairie pools, from a hundred 

 yards to a half mile or so wide, exactly on the boundary-line, 49° X., just 



