638 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



the entire egg. They also stand out nearly at right angles to the sur- 

 face of the egg, and while thej^ are really attached at random, yet 

 there is an average of about one on either side of each egg in the row, 

 so that, viewed as a whole, the}' are at fairly regular intervals. This 

 feature is sufficient to distinguish the eggs at once from any others 

 that are known. 



The eggs are small, measuring 0.375 by 0.275 mm. exclusive of the 

 jelly, light yellow in color and quite clear when first laid. But they 

 speedily turn darker in color and become opaque within the first two 



£7,5 /ii m 



Fig. 15. — An egg of ARGULrs americants approachixg mati'rity. The fully formed larva 



CAN BE SEEN THROUGH THE JELLY ENVELOPE. 



days. Toward the middle of the .second week, about the tenth day, 

 the eyes appear as two jet black large-sized spots near one end of the 

 egg. These spots are elliptical in shape, with their longer diameters 

 inclined toward the central axis of the egg, which is also that of the 

 embryo. 



The egg now begins to clear and becomes more and more trans- 

 parent up to the time of hatching. Through the membranes and the 

 jelly can be seen the outline of the embryo's body and appendages. 

 These can not be distinguished as plainly as in rnegalojps, for many 

 reasons. The jelly covering the egg is not as transparent as in 

 viegalojpfi and the papillte render it still more opaque. Again, the 

 partial development of the appendages renders it possible to pack the 



