THE BRINE SHRIMP OF GREAT SALT LAKE. 21 



late to fertilize the eggs for they have passed from the ovaries 

 into the ovisac and are covered with a brown shell and are ready 

 to be deposited. These eggs, deposited during April and May, 

 hatch within twenty-four hours after being laid. 



A comparison of these newly deposited eggs with those col- 

 lected during the early spring showed no particular difference, 

 except that none of the new eggs were cup-shaped as are many 

 of the winter eggs, Plate III., A. Examination of a number of 

 females showed the number of eggs to vary between sixteen and 

 one hundred and twenty. The females deposit their eggs while 

 swimming. 



Eggs were collected March 8 and kept in the laboratory in 

 normal lake water for twenty-one days. The room temperature 

 apparently had little effect upon the development since nauplii 

 were collected in the lake three days after individuals were 

 observed in the aquarium. 



The embryo transforms into a nauplius much unlike the adult, 

 Fig. E, Plate III. It has a blood-red color, a median eye 

 (ocellus) and three pairs of appendages, the first of which develop 

 into the first pair of antennae, the second pair are much larger 

 and serve as swimming organs, while the third pair become the 

 mandibles. After a few days the second pair, in females, become 

 shorter, less movable, lose their bristled margins, and are trans- 

 formed into small scarcely movable processes, the second an- 

 tennae, Plate II., B. In the males they also form the second 

 antennae which develop into disproportionately large claspers 

 with broad lobes, Plate II., A, and are used as catching and 

 clasping organs. Along with the early development of these 

 are signs of segmentation which is followed by the appearance 

 of the thoracic appendages one pair after another until all eleven 

 pairs have been laid down. The stalked compound eyes appear 

 about the same time as the first thoracic appendages. Within 

 eighteen to twenty-one days thue animals reach sexual maturity, 

 shown by copulation. Sexual differences become apparent when 

 the animals are a little more than half grown. The males are 

 stronger and more active than the females. 



Siebold's conclusion that Artemia may reproduce partheno- 

 genetically is verified by my observations. Water was taken 



