338 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



collectors the successive stages in the history of a single species. Like the adults, they are widely 

 distributed, and a gap in a series from the North Atlantic may be filled by a specimen from the 

 coast of Australia or the Sandwich Islands, and the collection from a single locality may contain 

 the larva} of several widely -separated species of adults in all stages of growth as well as the larvae 

 of deep-water species which are as yet entirely unknown. 



The attempt to unravel the tangled thread of the larval history of the Stoiuatopods is there- 

 fore attended with very exceptional difficulties, and the earlier writers were content to rest after 

 the bestowal of generic and specific names upon the larva?. As I found after the Challenger collec- 

 tion was placed in my hands that it was very rich in larva?, I attempted to determine, by compari- 

 son, the larval series for each genus, and the methods which I employed for making the comparison 

 are fully stated in my report. As one of the results of this comparison 1 ventured to describe the 

 general characteristics of the larva of the genus Gonodactyhis (p. 113), and in PI. xn, Fig. 5, of 

 that report I figured a larva which I ventured to call the larva of Gonodactylus. A comparison of 

 that figure with PI. xv, Fig. 11 of this memoir will show that this determination was correct, for 

 the larva of Qonodactylus chirayra which is here described is so much like the one figured in the 

 Challenger report that they belong, in all probability, to the same species. 



