NATURAL HISTORY OF AMERICAN LOBSTER. 
339 
toward the close of this period they become more sluggish, as if already affected by those 
profound changes which at the next molt deprive them of their rowing organs and start 
them upon a new career. Upon the bottom, however, the third-stage lobster is nearly 
as helpless as at an earlier period, and while it may make the attempt to steady itself 
upon its legs, it can not long maintain an upright position. Its future balancing organs 
Fig. 42. — Third larva, or third swimming stage of the lobster, drawn to a scale reduced from that of figures 34 
and 41. See legend of figure 34. Length 11.1 mm., or 0.44 inch. 
are still in an undeveloped state. The swimmerets are now fringed with short rudi- 
mentary setae, but do not come into full play until after the next molt. 
As Hadley has pointed out, at birth the larval appendages are less concentrated in 
the head region than in the adult state, and this is most noticeable in the maxillipeds, 
the exopodites of the third pair of which are used for swimming. From the first stage 
