34 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



which differ in shape in each species. Although the pulvillus has been 

 noted and depicted bj^ some speciaKsts on the Anostraca, I can find 

 no description of the cuticular elaborations of its surface. 



Most species of Branchinecta have, on the dorsolateral sides of the 

 entu'e trunk, more or less conspicuous rounded elevations, or bosses, 

 covered with cuticular papillae, with one or several sensory hairs near 

 the center (see Linder, 1941, figs. 20 and 22). These papillose bosses 

 are very poorly developed in Br. cornigera, new species, and often 

 appear to be absent on one or both sides of some segments. 



The shape of the endopodite of the thoracic feet and the structm^e 

 of the spines on its distal end and median border are both strikingly 

 different in the male and female (figs. 7, 8). Such a sexual dimor- 

 phism in the endopodites appears to be the rule in the genus, although 

 Br. gigas, in which the thoracic feet are practically alike in both sexes, 

 is an exception. The endopodital spines, especially those of the males, 

 constitute a minor specific character (figs. 5, 6). 



Distribution and environment: Branchinecta cornigera, new 

 species, has been collected from 30 temporary ponds in Grant, Lincoln, 

 Spokane, and Adams Counties in eastern Washington. The total 

 number of separate collections is 43, all of which were made from late 

 March to the middle of May. The species is typically present in 

 clear or slightly tm-bid water with a variety of other fresh-water 

 organisms, and often is associated with other species of phyllopods. 

 Br. cornigera was the sole phyllopod in 25 of the 43 collections; it was 

 associated with Euhranchipus serratus 13 times; with Eu. serratus and 

 Lynceus sp. once; with Eu. bundyi once; with Br. mackini twice, and 

 with Br. mackini and Br. gigas once. The temperature of the milieu 

 water ranged from 42° to 59° F. On 15 occasions the pH of the water 

 was ascertained with a Hellige Pocket Comparator. The water was 

 only moderately alkaline, the pH ranging from 7 to 8.8. In the pond 

 where Br. cornigera was associated with Br. gigas and Br. mackini the 

 water undoubtedly was much more alkaline (probably pH 10 or more), 

 but unfortunately the pH was not taken in that case. 



Remarks: I have been unable to accept the shuffling of specific 

 names proposed by Dr. J. G. Mackin (1952) for the following reasons: 



Packard's (1883) description of Br. lindahli is so deficient and brief 

 as to be meaningless, and is not accompanied by illustrations. It is 

 not possible to recognize the species from the description. 



Packard's original (1874) description of Br. coloradensis is entirely 

 inadequate, and the drawings are so trivial and devoid of essential 

 detail as to be without taxonomic utility. This description was 

 based upon one female from an altitude of 12,500 ft. in the Colorado 

 Rocky Mountains, and about 100 specimens of both sexes from the 

 indefinite locality of "Colorado." Packard's second (1883) description 



