232 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



stone. We found here, August 29, seemingly in consequence of this fact, an extra 

 ordinary abundance of mollusks; large Limnwa; in the grass at the margin, a small 

 Planorbis, Pisidium, Sphwrium, etc. Gammarus occurred here under stones, and 

 numbers of Allorchestes dentatus were taken in the weeds. 



The insects collected were species of Hydaticus and Hydroporus, Notonecta and 

 Corisa, caseworms, and Chironomus larva?. A few water-spiders (hydrachnids) were 

 taken among the weeds, and on the stones were great numbers of the cocoons of the 

 large leech, Nephelis maculata. Young of this leech were numerous, and an occasional 

 adult was seen, with specimens of Clepsine ornata and other species of the genus. 

 The most abundant entomostraca were Daphnia schoedleri and Diaptomus siciiis, var., 

 frequent specimens of D. shoshone occurring with the latter. That this large species, 

 previously found only in the larger lakes, should replace here in this shallow pond the 

 Diaptomus lintoni elsewhere characteristic of shallow water, was another of the sur- 

 prises of distribution and association of which these mountain lakes are fruitful. The 

 other small Crustacea noted were Cyclops, Eurycercus, Alona, and several species of 

 Cypris. The occurrence of tipongilla here is also worthy of mention. 



Oardiner Lakelet. Similar to the foregoing in -geological situation, but smaller, 

 deeper, and surrounded by deep and broken hills, is. a little pond formed in the course 

 of a swift and rocky stream to the west of Gardiner River, between Mammoth Hot 

 Springs and the town of Gardiner. It is about 250 yards long by three-fourths as 

 wide, and 20 feet deep in the interior, with its marginal waters filled with a strong 

 growth of rushes and other vegetation. It was full of eutomostraca, gammarids, and 

 insects. On the stones were great numbers of the egg capsules of the common large 

 leech, Nephelis maculata, and many young of this species were crawling about, but 

 the time for the adults had apparently gone by. The assemblage of entomostraca 

 was again peculiar, the most abundant form being a Ceriodaphnia, and the next 

 commonest a medium-sized Diaptomus (mostly immature), described on page 253 as 

 a new species under the name of />. piscince. There were also many specimens of 

 Cyclops, an occasional Daphnia pule.v, and several of Ghydorus, in a collection obtained 

 by drawing the surface net through the open water. Chironomus lar vre were, of course, 

 abundant; and worms of various kinds, small flat planarians, larvae of Agrion and 

 Dytiseidm, species of Haliplus, Corisa, and Notonecta, larvse ofLibellulw and ephemerids, 

 species of Clepsine and of Physa, were represented in our collections. 



Small ponds. Occasional roadside collections made from small standing pools 

 will be of interest chiefly because of the locality and altitude. The ordinary contents 

 of such waters at the time of our visit may be learned from the following lists: 

 Weedy pool between Norris Basin and Grand Canon, August 21, 1890: 



Chirouomus larvae (a few). 



Corethra larva (one). 



Corisa larvae (three). 



Diaptomus lintoni (many). 



Cyclops (a few). 



Polyphemus pediculus (a few). 



Daphnia pulex (many, with ephippia). 



Daphuia schoedleri (a few). 

 Scapholeberis mucronatus (very many). 

 Ceriodaphnia reticulata (many). 

 Chydorus spha'ricus (very many). 

 Macrothrix sp. (one). 

 Acroperus leucocephalus (one). 



