48 Eobert E. Coker. 



not be said that tliis paper includes experimental observations of 

 more than suggestive value. The observations given below were 

 made on such of the embryos (and nev^^born) as were old enough 

 for the scutes to be clearly distinguishable. 



Before proceeding to the tables a word should be said as to the 

 normal conditions of development. 



Observations on Conditions of Development. . 



The loggerhead sea-turtle makes its nest in the region of Beau- 

 fort, at or near the base of the sand-dunes that line the beach at a 

 short but varying distance from the water. The nest is subspher- 

 ical, somewhat flattened on top, and packed with eggs usually to the 

 number of 120-150. The top eggs are 12 to 15 inches below the 

 surface, and, as the nest is 10 inches or more in diameter, the bottom 

 eggs are 22-24 inches below the surface. At this depth, the bottom 

 eggs may be below the level of the high tides, or as much as 4 feet 

 above it, according to the elevation of the ground at the foot of the 

 dunes.^ 



As the shell of the egg is soft and, in its new-laid condition, not 

 completely filled, it displays a characteristic movable dent, like a 

 rubber ball incompletely filled with air. In the course of develop- 

 ment the contents increase in bulk and the shell becomes filled out 

 and spherical : it may even be tightly distended. Agassiz says, "The 

 older the egg the more distended does the shell appear." I have 

 not found that the distension occurs invariably or to a uniform 

 degree. The degree of distension varies with external conditions. 

 Distension generally takes place, and it may occur to an extreme 

 degree. With a large number of eggs massed together deep under 

 the sand, the swelling of the eggs must cause great crowding and 

 coYisiderable intei-pressure. In one nest, for example, the eggs were 

 so distended that upon a single puncture of a shell with a needle, 

 a fine stream of fluid would squirt out a distance of several feet 

 and the shell burst widely in the hand. Even though many of the 

 eggs that failed to develop shrunk in size so as to be almost flattened 



*See also my paper, '00. pp. 01 to 05. 



