BIOLOGY AND NATURAL HISTORY 227 



Egg laying is accomplished on sandy beaches — which generally are not 

 too abundant in areas of salt marshes. In late spring or early summer (May, 

 June, and July at Beaufort in the artificial pens) the female using her hind 

 legs excavates a jug-shaped cavity about 3 inches in diameter and 6 to 8 

 inches or more in depth. In this she deposits a number of eggs. Five to 

 about 15 eggs have been found in a nest, but a female may lay 4 or 5 times. 

 The cavity is then filled, the eggs being covered to a depth of several inches, 

 and the sand tamped down. After the female makes the nest inconspicuous 

 by crawling back and forth over it, the eggs are left to their fate. Hildebrand 

 concluded that, under good conditions of terrapin culture, about 12 eggs 

 per female per year may be expected. 



In the experimental pounds terrapin may begin laying at about 6 years 

 of age and continue to do so for at least 10 j'-ears. Annual mating is not 

 required, since female terrapin have facilities for retaining sperm in good 

 condition for several years. Females isolated from males after mating pro- 

 duced fertile eggs for four years, although the proportion of fertile eggs 

 diminished rather rapidly after the second year. Since a male may fertilize 

 several females, it is not necessary to keep for breeding purposes an equal 

 number of males and females: one male to 5 females seems to be adequate. 

 As a matter of fact, in the breeding pens at Beaufort the sexes, without 

 selection, developed in about this proportion. 



The period of incubation of the eggs is about 90 days, varying with tem- 

 perature and other conditions. The exact duration is difficult to determine, 

 since the young do not usually emerge from the nest until several days after 

 hatching. The newly-hatched young, about 1M2 inches (27 mm.) on the 

 bottom shell are relatively helpless, and may fall easy prey to crabs, fish, 

 birds, and rats. What the survival rate during the first year may be in nature 

 is quite unknown. In respect to survival in the experimental pens, under 

 conditions of substantial protection from most enemies, Hildebrand (1926) 

 reported, that about 60 per cent of the terrapin hatched came to maturity, 

 a reasonable proportion in comparison with the survival rate in poultry 

 production. The mortality rate in nature may be presumed to be much 

 higher. 



The chief causes of mortality in pens were disease and unpreventable 

 depredations of enemies, chiefly rats; some possibly escape. The common 

 diseases were described as "sores," referred to by Hildebrand as cancerous, 

 "soft-shell," associated with failure to eat and subject to rapid recovery, 

 and "limber-neck," a form of paralysis from which recovery is rare. 



Young terrapin in nature or in confinement, unless kept warm, were not 

 observed to eat; there is, then, no growth in size until the spring of the 

 following year. It was found at the Beaufort Laboratory, however, that 

 if the baby terrapin are kept in warmed nursing houses during the first 



