92 Branchipus. 
the Phyllopod Crustacea of North America," ^ Dr. Paul F. Gissler 
gives the results of his efforts to obtain the larvae from dried mud : 
"During the whole summer of 1880 I experimented with dry 
mud from ponds inhabited by either the norma'l or pale race of this 
Branchiopod, but all in vain. Neither jars kept on ice in a large 
refrigerator, nor frozen dampened mud, gradually or suddenly 
thawed, developed any larvae. The mycelium of a fungus, a few 
Daphniidae and microscopic organisms were the only result." 
Some time during April, 1888, the junior author collected a con- 
siderable number of females of B. vernalis, and selecting such as 
had their ovisacs filled with eggs, put them into a jar of water, m 
the bottom of which was placed earth taken from the garden. 
These females were allowed to remain here until they died, which 
was within about two weeks. The water was allowed to evaporate, 
the mud became dry and was moistened only once or twice during 
the summer. It was, of course, as dry as dust the greater portion 
of the time. On September 27, this dirt was broken up and put 
into another jar and covered with water. Immediately numbers of 
the eggs came to the surface and remained floating there about 
two days, when they went again to the bottom. On October 9, lar- 
Vcc were, for the f^rst time, observed swimming about iu the jar and 
soon large numbers appeared. This experiment proves that the 
hatching of the larvae of B. vernalis is by no means difficult to 
bring about, and that we may almost at will obtain them for obser- 
vation. It also shows that it is not necessary that the eggs should 
ever be subjected to a freezing temperature. 
That we have in our experiments succeeded in getting a view of 
the larva immediately after their exclusion from the eggs, we are 
not wholly certain. They could, at all events, have escaped but a 
short time before they were seen. One specimen was observed 
while in the act of escaping from the egg-shell ; but the specimen 
seemed to be unable to extricate itself and may have been sticking 
there for some time and meanwhile undergoing change. 
One thing, however, appears to be evident, namely, that the 
larva differs in some important respects from that of B. sta^nalis as 
figured and described by Dr. C. Glaus in his paper, "Z//r Kenntntss^ 
des Baues und Entivickelung von B. stagnalis und Apus cancrifonnis; 
" U. S. Geol. and Geog. Survey Wyoming and Idaho for 187S. Washington, 
