PACKARD ON NEW PHYLLOPOD CRUSTACEA. 179 



differs from any others in the remarkably short telson, which is short and 

 broad, nearly one-half as Ion g in proportion as in X. couesii. The segment 

 is broader at base and the telson is broader than in any other species ; it 

 is truncate at the end, and divided by a slight incision into two well- 

 marked lobes, with about seven more or less well-marked median spines 

 on the blade of the telson ; this segment, including the telson, is as long 

 as the preceding segments collectively. In the carapace, seen from be- 

 neath, the distance from the anterior edge of the hypostoma to the 

 anterior edge of the carapace is much less than in L. couesii, while the 

 hypostoma itself is much more convex. The antennae are much longer 

 and broader than in L. couesii. The first (shortest) branch is broad, not 

 so long as in L. couesii; the second branch extends nearly two- thirds of 

 its length beyond the edge of the carapace; third branch a little more 

 than twice as long as the second, while in L. couesii it is but slightly 

 longer than the second. The feet are broader than in L. couesii. Length, 

 including caudal filaments, 48™™; length of carapace (measured along 

 median line), IS™™; breadth, 18™™; caudal appendages, 17^™™; antennae, 

 15™™. 



Female. — Differs from the male in the much shorter body and shorter 

 antennae. There are fivesegments beyond the last pair of feet, and twelve 

 segments beyond the edge of the carapace. It is easily distinguishable 

 by the shorter abdomen and antennae, but otherwise it does not differ, 

 the telson and caudal filaments being of the same proportion. The egg- 

 sacs were empty; they are situated on the tenth pair of feet. Length 

 of body, 35™™; length of carapace (measured along median line), 15™™; 

 breadth, 17™™; length of caudal appendages, 14™™; antennae, 10™™. 



Po Caiion, Vermillion River, Colorado ; collected by Dr. C. A. White, 

 of Major Powell's Survey. Described from specimens kindly loaned by 

 Prof. H. A. Ward, of Rochester, N. Y. 



This exceedingly interesting species di'ffers from any other known to 

 me in the large, broad, bilobed telson, that ofL. glacialis being small, sub- 

 triangular, while in L.productus and L. couesii it is long and spatulate. 

 It differs from the two latter species in the longer, broader, second an- 

 tennae, the longer body, and shorter carapace. 



North America seems to be richer than Europe-Asia in the species of 

 this genus, one only occurring in the Eastern Hemisphere, while three 

 species occur in North America, one in Greenland and Arctic America, 

 and two on the plains and caiions east of the Rocky Mountains. No 

 species of the family have as yet occurred east of the Mississippi River. 



Apus lucasanus Packard (Amer. Jour. Sc. Arts). — This species occurred 

 in great abundance at Ellis, Kans., associated with the other Phyllopods 

 from this locality. It was collected in June by Dr. L. Watson. The 

 specimens are not distinguishable from my types of A. lucasanus from 

 Cape Saint Lucas, Lower California. 



Note. — Figs. 11, 13, 14, and 1.5 were drawn under my direction by Mr. J. S. Kiugsley, 

 and Figs. 12, 16, and 17 by Mr. J. H. Emerton. 



