NATURAL HISTORY OF AMERICAN LOBSTER. 
347 
piles, the tops or surfaces of which are sometimes laid bare at unusually low tides in 
fall, when they may be found by digging and turning over the stones, at depths of but 
a few inches at low water, but where at the flood the sea rises to a height of 5 feet or 
more. The smallest, from about to 3 inches in length, go deep down among the 
loose stones, where no enemy is likely to reach them. At a later period, when from 
3^2 to 4^ or 5 inches long, they issue from their retreats more freely and explore the 
bottom with greater boldness. They also dig caves under stones, from which, as at an 
earlier period, they stealthily crawl in search of prey, but quickly return when an enemy 
appears. We have seen that this characteristic burrowing instinct develops as early 
as the fourth stage. 
As the lobster increases in size it becomes bolder and retires farther from the 
shore, but it never loses its instinct for digging nor abandons the common habit of 
concealing itself when the necessity arises. 
A LOBSTER 413 DAYS OLD. 
As is well known, size, whether of lobsters or of mankind, is not a certain criterion 
of age. In the crustacean it depends upon the number of molts successfully passed, 
while unfavorable conditions tend to lengthen the molting periods. Some of these 
conditions will be considered in a later section. This was well illustrated by the young 
lobster whose history follows. This animal was reared in a small glass aquarium at 
Woods Hole, Mass., and was fed with minced clams and the eggs of the lobster and cod. 
It lived from June 20, 1893, until August 6, 1894, when it had attained the length of 
36 millimeters (1.44 inches). 
In its final stage the colors of the animal had apparently reached the limit of their 
brilliancy and the mottled color pattern was as complex as in an adult animal. The 
body was of a light umber color freely speckled and mottled with darker tints. The 
appendages were reddish brown and slightly translucent. Small light spots or suffus- 
ions were found in certain parts of the body; the tendon marks, corresponding to those 
characteristic of the fifth and later stages, were prominent, the round spot just below 
the cervical groove being over a millimeter in diameter ; the pleura of the first abdominal 
somite were snowy white, while the free edges of the segments of the body and of the 
appendages were bright blue; the large chelae were white tipped. The openings of the 
oviduct were plainly visible, while the lips of the copulatory pouch or seminal receptacle 
were not yet closed. The color of the appendages on the under side was light reddish 
brown, and the tail-fan was of the same hue, edged with deep red; the big claws, which 
were tufted with setae at their tips, showed but little differentiation. The compound 
eyes had acquired the large size and prominence of the later adolescent stages. 
WHEN DOES THE YOUNG LOBSTER GO TO THE BOTTOM TO STAY? 
Over 15 years ago I raised the question which is now placed at the head of this 
section, and answered it in a tentative way, but its importance seems to have been 
underestimated, for it has received little attention from other workers up to the present 
time. 
