700 LOUIS AGASSIZ. 



served to keep the central mass floating, cra- 

 dle-like, between them. The elastic threads, 

 which held the ball of Gulf weed together, 

 were beaded at intervals, sometimes two or 

 three beads close together, or a bunch of them 

 hanging from the same cluster of threads, or 

 occasionally scattered at a greater distance 

 from each other. Nowhere was there much 

 regularity in the distribution of the beads. 

 They were scattered pretty uniformly through- 

 out the whole ball of sea -weed, and were 

 themselves about the size of an ordinary pin's 

 head. Evidently we had before us a nest of 

 the most curious kind, full of eggs. What 

 animal could have built this singular nest? 

 It did not take long to ascertain the class to 

 which it belonged. A common pocket lens 

 revealed at once two large eyes on the side 

 of the head, and a tail bent over the back of 

 the body, as in the embryo of ordinary fishes 

 shortly before the period of hatching. The 

 many empty egg cases in the nest gave prom- 

 ise of an early opportunity of seeing some 

 embryos, freeing themselves from their envel- 

 ope. Meanwhile a number of these eggs con- 

 taining live embryos were cut out of the nest 

 and placed in separate glass jars, in order to 

 multiply the chances of preserving them; 



