1 94 THE A ME RICA N NA TURA LIST. [Vol. XXXV 111. 



emerged into the water this respiratory rhythm was gi-adually 

 perfected. Two minutes after the larva had first straightened 

 itself out in the water the scaphognathite was seen to swing 

 back and forth but with some stops. Before that at the time of 

 straightening of the body, there were only a few jerky contrac- 

 tions and then, after a minute or more, one or two swings. 

 Five minutes after the body had straightened out in the water 

 the scaphognathite was not in regular swing and even ten 

 minutes was not long enough to acquire an uninterrupted, regular 

 beat. 



In some unobserved manner this first or preliminary larva 

 frees its abdomen from the skin within the egg-case, but still 

 remains holding fast by its claws. This larva is about 4 mm. 

 long and lives this life of restricted freedom for only about 48 

 hours and then moults into a second stage. 



Second larval stage. — As the first larv^a is attached only by 

 its claws we would expect that when it moulted it would become 

 loose and no longer connected with the parent, but such is not 

 the case since it again possesses an anal fastening and later holds 

 by its claws anew. When the moulting takes place the trans- 

 parent skin of the larva breaks along the back and the back and 

 head of the larva slowly push out through the rent. Then the 

 antennules and antennae are pulled out of the old skin and for 

 the first time thrust forward into the permanent anterior posi- 

 tion instead of being carried backward in the embryonic position 

 retained in the first stage. The legs are pulled out of their old 

 skins and kick about in the water ; then the abdomen is bent 

 free, all but the tip, where the anal region remains fast to that 

 region of the cast skin and does not break loose even when it flaps 

 vigorously. As the shed skin still has its claws fast locked 

 in the egg stalk the larva though it has drawn its hands out of 

 its gloves, as it were, and come out of its old clothes, still 

 remains indirectly fastened to the mother since its telson is fast 

 to its old suit and that is not broken but continuous with the 

 gloves, or claw skins. At first the movements of the legs make 

 the larva seem to be trying to crawl upon the cast skin but 

 after a few minutes the large claws are opened and reaching 

 about take hold of the shed or of the egg case. After many 



