354 GEOLOGICAL SURVEY OF THE TERRITORIES. 
and bilobed, there being two short terminal tubes, with distinct, large 
openings, directed downward. 
Female-—Second antenne large and long, extending back a little be- 
yond the base of the ovisac, oar-like, expanding broadly on the outer 
two-thirds, especially on the upper edge. The ovisac is subconical, the 
base broad and concealed by the limbs; it terminates at the posterior 
edge of the fourth segment from the end, ending in two unequal flaps, 
the upper four times larger than the under flap, and triangular in out- 
line. 
Length of male, 23™™; female, 26.5™™, Ellis, Kans., Dr. L. Watson, 
collected June 26, 28, and 29, and again September 27, Octo- 
ber, 1, 10, and 22, 1874, in.pools of water on the plains, in 
company with Estheria and Limnetis. A fully-grown male 
occurred September 27th. October 1-22 females of full size 
were collected, in company with Apus lucasanus, Estheria com- 
\ pleximanus, and LEstheria mexicana.* The ovisacs still con- 
tained eggs, though empty at the ends. 
No striking variation Was observed among several hundred 
specimens of different ages. Dr. Watson writes that the gen- 
eral color is pinkish, the 
edge of the tail red, and 
the genitals light blue. 
The sexual characters 
are very distinct when 
the animal is one-third 
grown, the oviducts 
being red with eggs, 
and the males with the 
frontal bush-like appen- 
dage well developed. 
: 4 The following account 
naa Ee anceioes ae tenn aes aa af Boas of reac aR of the occurrence in 
ONASAC: Kansas of this interest- 
ing genus, and of Apus lucasanus, Streptocephalus texanus, Hstheria 
mexicana, and Limnetis I extract from a letter of Dr. Watson, dated 
Hllis, Kans., October 12, 1874: 
The Apus moves about on the bottom of the pools, rarely rising enough 
to allow the slipping of the net under him, and is not easily captured 
unless in close quarters. The Estheria and Limnetis swim about, go- 
ing to the bottom and coming to the surface, and are easily captured by 
slipping a net under them when up. The Thamnocephalus are always 
in medio, and by gentle action are easily taken. The forked-tail ones 
(Streptocephalus) at the edge of the pool, and the larger emarginated- 
tailed ones always in the middle, or in circumscribed clear places having 
6 or 12 inches of water. The heavy rain of June 14 washed out the 
ravines by torrents. The dates I have before given for former collections 
indicate the development of those specimens after that date. Those 
now sent (October 14) have developed, certainly since September 2; 
probably since September 8; possibly since September 13. 
‘In relation to the localities where I have found the Crustaceans: 
‘“There are “divides” upon these plains, between streams; just here, 
*From Mr. R. P. Whitfield we have received specimens of Hstheria mexicana collected 
by Dr. C. A. White, on the Vermilion River, Colorado, in company with Lepidurus 
dbilobatus Pack. See American Naturalist, xiv, 53, 1880, where this species is referred to 
under the name of Estheria watsoni Pack. (uo description), which is synonymous with 
E. mexicana, 
