42 UNIVERSITY OF COLORADO STUDIES 



Thamnocephalus plalyurus Packard was discovered at Ellis, Kansas, and has not 

 been reported from Colorado, but good specimens of both sexes were found by 

 Mr. H. C. Markman in a roadside pool, at Montclair, Denver County, July 15, 

 1908. The figure accompanying Dr. Packard's original description does not show 

 the deep lobing of the apex of the abdomen, but it is correctly described by him. 

 Slreplocephalus texanus Packard has been reported by Beardsley from the Mesa 

 de Maya (misprinted Mayo) in Las Animas County. Mr. Markman took it at 

 Montclair on July 15, in company with Thamnocephalus. I give a figure of the 

 second antenna of the male, modified for clasping. 



The Colorado species of Branchinecta have been fully discussed by H. L. Shantz 

 in Biological Bulletin, LX, pp. 249-264. B. coloradensis Packard occurs in the 

 mountains, B. lindahli Packard on the plains. B. lindahli can be distinguished 

 easily from B. coloradensis by the smaller eye and egg, by the difference in the 

 shape of the eye, by the greater number of eggs in the ovisac (often 50 or more in 

 lindahli, seldom as many as 30 in coloradensis), by the absence of the basal tubercle 

 on the second antennae of the male, by the difference in the tips of the second 

 antennae and by the longer and more slender caudal appendages (Shantz). 



Family APODLDAE 1 



Carapace well developed as a depressed shield, covering at least half the body; 

 eyes sessile; no male clasping organs. 



Telson not produced backward as an ensiform plate . . . Apus Scopoli. 

 Telson produced backward as an ensiform plate, entire in L. couesii Packard (Utah, 

 Montana), emarginate in L. bilobatus Packard (Colorado) . . Lepidurus Leach. 

 Apus obtusus James, 1823 (longicaudatus Le Conte, 1845), was described from rain- 

 water puddles on the Platte River, near the Rocky Mountains. The type of 

 longicaudatus came from the Rocky Mountains, near Long's Peak. Mr. Markman 

 collected numerous specimens of this species at Montclair, July 15, in company 

 with Thamnocephalus, etc. The little spines at the caudal end of the abdomen 

 are variable. 



Family LIMNADILDAE W. Baird 

 Body compressed, with a carapace in the form of a bivalve shell; second antennae 

 alike in both sexes; the first or first and second thoracic limbs prehensile in the 

 male. The following key is mainly based on that of Weldon: 

 Carapace spheroidal, without lines of growth; only the first thoracic limbs pre- 

 hensile in the male (subfamily Limnetinae Packard) 



Limnetis Loven (Kansas, Montana). 

 Carapace otherwise, with concentric lines of growth; first and second thoracic 

 limbs prehensile in the male (subfamily Limnadiinae) .... 

 Carapace with the valves oval or oblong, with well-marked umbones and 



numerous lines of growth Estheria Ruppell. 



Carapace with the valves narrowly ovate, with only four or five lines of growth 



Eulimnadia Packard. 

 At Montclair, July 13, along with Thamnocephalus, etc., Mr. Markman took 

 ■ Apidoe Burmeister, not Leach. 



