360 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



tlie three pairs of free thoracic legs, and the uropods are represented by buds. An umber of moults 

 and probably aii interval of many weeks intervenes between this stage and the one shown in PI. xv, 

 Fig. Jl of the Challenger report. 



The life history of this species of Gonodactylus, in the Bahama Islands at least, is thus seen 

 to bo extremely simple. It hatches as an Erichthus and remains an Erichthus until it assumes its 

 adult form ; and as the successive appendages make their appearance they have from the first the 

 structure which they are to retain through life. The statement which I made in my Chullcnt/cr 

 report (p. 55), that Gouodactylus hatches from the egg in the Krichthoidina stage and subsequently 

 changes into an Erichthus, is an error, at least so far as Gonodactylus chiragra is concerned, 

 although it is possible, in view of the great variation which we have observed in a single species 

 of Alpheus, that in other regions, where the adults have different habits, the larva may hatch in a 

 younger stage. Coral-dwelling Crustacea seem to exhibit a tendency towards the abridgment of 

 their metamorphosis, and it is not at all improbable that other species of Gouodactylus may have 

 an Erichthoidina stage. 



The Challenger collection contains a bottle of very minute and young larva- in the Erichthoi- 

 dina stage, and one of these is shown iu Fig. 3 of PI. XII of my report. Comparison between this 

 and the newly hatched Erichthus of our species, PI. xiv, Fig. .'3, will show many points of resem- 

 blance, and future research may possibly prove that it is the larva of Gouodactylus, although the 

 statement that all Gouodactyli hatch as Erichthoidiua; is au error. 



