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THE AMERICAN NATURALIST [Vol. XLI 



A dissection of one of these second larvae revealed a mass of 

 membranous material and both simple and plumose setse in the 

 intestine suggesting that these larvae may eat the egg cases and 

 setse from the mother's pleopods. 



The creature was still translucent enough to show the ventral 

 ganglia through the exoskeleton of the abdomen and was dotted 

 over with pigment cells of stellate form, which when expanded were 

 light red and when contracted very dark, while deeper in were 

 diffuse and indefinite blue cells. In the antennae and legs as well 

 as in the antennal artery the corpuscles were going outward rapidly 

 and returning somewhat more slowly in wider vessels. 



Two days before molting into the third stage the new inner 

 cuticle was already formed and the new setse projected into the 

 bases of the old. The yolk had become reduced to a small dark 

 remnant on either side and even to the naked eye the gastroliths 

 were conspicuous as two pink-white opaque areas, one on each 

 side of the stomach enveloped in a clear glassy coat. 



The third stage began by June 1st and had the adult character 

 of a tail-fan made of the telson and the fully expanded sixth pleo- 

 pods all fringed with perfect plumose setae. These larvae were 

 10^ to 11 mm. long, 3 wide and 2h deep and expanded the tail-fan 

 about 4 mm. while the antennae were 6 mm. long. 



These third stage larvae when recently molted were still some- 

 what translucent and of a faint pink color with red-tipped claws 

 and though the stomach was plainly visible the gastroliths were 

 lacking on the outside. But within the actively moving stomach 

 was a brownish liquid containing white particles or in some cases 

 whole gastroliths moved about actively. In some cases the intes- 

 tine contained colored material in its anterior part. 



The specific gravity of the larvte had so changed tliat they now 

 floated in Worcester's liquid though the first and sf'cond stages 

 sank; they were also less resistant to this fluid and died more 

 quickly than when vounger. 



When the iarvH- luid chanovd int.. th<- third Mauv it wa. noted 

 that the six mothers no hniger had egg cases an.! ea.t .Miti. le> upon 

 their pleopods and as their fa>ees containe.l part.> of phnn.^e set;e 

 of adult size it may be that they aided in cleaninu' ..tf their pleojwds 

 though there is some evidence that the second hirva- may eat off 



