2<)4 BULLETIN OF THE BUREAU OF FISHERIES. 



When the eggs have all been deposited, the turtle's leg's are again put in requisi- 

 tion, this time to till up the hole, which is done by alternate motions as before. 

 The earth about the hole is used at first, but search is made for more loose earth 

 for a little distance, as far around as the leys can reach with a slight motion of the 

 body cither to the right or left without moving the front legs. Toward the end of 

 the process the loose earth is trampled down. When the hole is well tilled up to 

 the level of the ground, the turtle turns around and goes immediately down into 

 the water, not casting even one backward glance. 



I have noticed an interesting contrast between the behavior of Trionyx and of 

 Clemmys during the egg deposition. If one wants to watch a Trionyx depositing 

 eggs, one has to crawl on all fours behind the plank wall of the pond and peep 

 through a hole, being careful not to show* himself. The moment the snapping turtle 

 sees anyone, it stops in whatever part of the egg-laying process it may be engaged 

 and plunges straight into the water. Utterly different is the behavior of Clemmys. 

 When once it begins the process of egg-laying it is never deterred from canwing it 

 out, no matter how near or how boldly one may approach. Whenever I watched a 

 ( 7- iiimi/s working away in the direct midsummer rays with its carapace all dried up 

 and with its eyes alone moist, I could not helping comparing it to a slave of duty 

 fulfilling his fate with tears in his eyes. What causes such a difference of behavior 

 in the two species '. What is its significance? What difference in the nervous system 

 corresponds to it ; 



The traces of a spot where the snapping turtle has laid eggs are (1) the two 

 marks made by tin 1 forepaws holding on to the earth during the whole operation, 

 and (•-') a disturbed place some distance back of the line of the forepaws where the 

 hole has been made. The three marks are at the angles of a triangle. I have, 

 noticed a very interesting fact in regard to these traces. When a young female is 

 depositing her first eggs, she is very clumsy, the hole being badly made and the tilling 

 in of it very imperfect, so that often a part of it remains open. Old females are 

 extremely neat in their doings, and one can determine at once the age and size of the 

 female by the skill displayed and by the distance between the three marks of egg 

 deposition. This shows that although the elaborate actions necessary in ^gg laying 

 must lie, in the main, due to instinct, each individual lias to add its own experience 

 to the inherited impulses and is able thus only to accomplish the desired end with 

 perfection. 



In Hattori's farm a person goes around the " parents' pond" once a day or so and 

 covers up with wire baskets all the new deposits made.since the last visit (pi. II, tig. i). 

 Each basket may be marked with the date if necessary. This covering serves a two- 

 fold purpose — the obvious one of marking the place, and in addition that of keeping 

 other females from digging in the same spot. When hundreds, or even thousands, 

 of these baskets are seen along the bank of a "parents' pond," it is a sight to gladden 

 the heart of an embryologist, to say nothing of that of the proprietor. 



The hatching of the eggs takes, on an average, sixty days. The time may be 

 considerably shortened or lengthened, according to whether the summer is hot and 

 the sun pours down its strong rays day after day. or whether there is much rain and 

 the heat not great. It may become less than forty days or more than eighty days. 

 By the time the last deposits of eggs are made in the middle of August, the early ones, 



