172 



BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



motions. They swim about actively. The young Estlierioi are crawling 

 actively over the surface of the sediment. Temperature of the room 

 pretty uniformly 68°, rarely over 70° during the day, subsiding at night 

 to 50O or 40O." 



The collections made by Dr. Coues were from the Northern Boundary 

 line of the United States, latitude 49° north, in Montana Territory, and 

 are of great interest, from the discovery of a genus {Lepidurus) new to 

 temperate North America. 



Lymneiis hrevifrons, n. sp. (Fig. 11, c, front of head). — Many 

 females. Carapace decidedly triangular in outline, more so 

 than in L. gouldii, while it differs very decidedly in this re- 

 spect from gracilicornis, and is considerably larger than 

 graeilieornis or mueronatm, and is flatter than both. Front 

 shorter and broader than usual; less contracted in width 

 at the base of the antennre than usual. The frontal carina 

 is high, especially a little in front of the eyes. Compared with 

 that of Lymnetis graeilieornis (Fig.ll, b), it is much broader, 

 shorter, the keel reaching to the end, which is squarely 

 docked, the end being a flattened triangle ; the end of the 

 front reaches to the middle of the antennse, while in L. gra- 

 eilieornis the end reaches two-thirds of their length. It dif- 

 fers from L.gouldii (Fig. 11, d) in the front being thicker, the 

 truncated end forming, seea from the end, a much less flat- 

 tened triangle. 



Lower antennae considerably longer than in L. gouldii, 

 the terminal joint extending well beyond the end of the 

 Jl'^- }^-tK^°^^ front, while in L. qouldii it does not extend beyond the 



of head of Lym- i u ^ 



netis spp.— a, L. front : tlic uDDcr brauch of the flagellum has 22 ioints : 



miicronaUis ; b, L. ' 07 



graeilieornis; e,L. the lower, 20. (lu L. gouldH^ there are 14 joints in the 

 ■gouidii. ' ' ' uppcr, and 12 in the lower branch of the antenna.) There 

 are twelve pairs of feet. Terminal segment less prominent than in L. 

 mtieronatus, while the dorsal edge is less excurved. 



Average size of most of the specimens : Length, 4™°^ ; breadth, 3 J™™. 

 Several larger examples were 6™°^ long and 5^"^ broad. 



Ellis, Kans., June 28 and 29, Dr. L. Watson, in poojs, associated 



with several other species of Phyllopods. 

 A few eggs were contained in most of 

 them. This is the largest species known, 

 and is as a rule flatter and more trian- 

 gular than any other species, while the 

 truncate front of the head is shorter and 

 broader than in any other American spe- 

 cies yet known. 

 Lymnetis mueronatus Pack. (American 

 Naturalist, ix, 1875, 312) (Fig. 12, male, much enlarged, — «, hand, much 

 enlarged; Fig. 11, a, front of head of female, enlarged). 



Fig. 12. — Lymneiis mueroiiatus, Pack. 

 male; a, claw; both enlarged. 



