[:.:M1 [NVEBTEBBATE ANIMALS or VINKYAKI* SOUND, ETC, 237 



the abdominal legs or of any of the future legs <f tin- iiM---.ii.ip> ami 



crab. In this stage they are very small, much smaller than in t, 



figured. After they have increased \ ery much in si/..-, and have molted 

 probably several times, they appear as in the figure just referred to. 

 The terminal segment of the abdomen, seen only in a side-view in the 



6, is very broad and divided nearly to the base by a broa 

 each side the mar-ins project in long, spinitbrm, diverging processes, at 

 the base of which the margin of the sinus is armed with six toei-ht 

 spines on each side. When alive they are translucent, with deposits 

 of dark pigment forming spots at the articulations of the abdomen and 

 a few upon the cephalothorax and its appendages. In this stage they 

 were taken at the surface in Vineyard Sound, in immense numbers, from 

 June LM to late in August. They were most abundant in the early part 

 of July, and appeared in the greatest numbers on calm, sunny days. 



Several zoi'-a of this stage were observed to change directly to the 

 megalops form, (Plate VIII, fig. 38.) Shortly before the change took 

 place they were nor quite as active as previously, but still continued to 

 swim about until they appeared to be sei/ed by violent convulsions, and 

 after a moment began to wriggle rapidly out of the old xoea skin, and 

 at once appeared in the full megalops form. The new integument seems 

 to stiffen at once, for in a very few moments after freeing itself from the 

 old skin the new megalops was swimming about as actively as the oldest 

 individuals. 



In this megalops stage the* animal begins to resemble the adult. 

 The five pairs of cephalothoracic legs are much like those of the adult, 

 and the mouth-organs have assumed nearly their final form. The eyes, 

 however, are still enormous in size, the cam pax is elongated and h 

 slender rostrum and a long spine projecting from the cardiac region far 

 over the posterior border, and the abdomen is carried extended, and is 

 furnished with powerful swimming-legs as in the Macroura. In color 

 and habits they are quite similar to the later stage of the zoi : a> from 

 which they came; their motions appear, however, to be more re-alar 

 and not so rapid, although they swim with great facility. In this meg- 

 alops the dactyli of the posterior cephalothoracic Jegs are styliform. and 

 . ach furnished at the tip with three peculiar seta- of different lengths 

 and with strongly curved extremities, the longest one simple and about as 

 long as the dactylus itself, while the one next in length is armed along 

 the inner side of the curved extremity with what appear to be minute 

 teeth, and the shortest one is again simple. 



According to the observations made at Wood's Mole, the youn. 



er in-nt'tifus remain in the megalops stage only a very >imrt time, 

 and at the first molt change to a form very near that of the adult. 

 Notwithstanding this, they occurred in vast numbers, and were taken in 

 the (owing-nets in greater quantities even than in the /. < . Their 



time of occurrence seemed nearly simultaneous with that of the / 

 and the two forms were almost always associated. The exact time any 



