THE DIAMOND-BACK TERRAPIN. 93 



Table i.— Records of Breeding Stocks of Terrapin in Captivity at Beaufort. N. C— Con. 



Stock and year. 



Eggs. 



Number. 



Rate per 

 female. 



Young. 



Number. 



Rate per 

 female. 



Per cent 



eggs 

 hatched. 



Second stock 



19" 



1912 



1913 



1914 



i9'5 



1916 



1917 



1918 



1919 



1920 



Texas stock: 



1912 



1913 



1914 



1915 



1916 



1917 



1918 



1919 



1920 



649 



673 



74S 



958 



871 



" 973 



"731 



° 773 



1, 172 



I-'7 

 292 

 412 

 399 

 421 

 497 

 (') 

 270 

 138 



9.0 



9 4 

 10. 4 

 13- 4 



136 

 2 154 

 1 11. 5 

 'I5-4 

 c 13- I 



3-7 

 8.5 

 12. I 

 II 7 

 16.8 

 19.8 



M 



24.5 

 <■■-' 5 



583 

 606 

 724 

 876 

 783 

 805 



a 670 



a yo2 



1. 133 



IOI 



281 

 376 



366 



383 



439 

 (') 



8.3 

 8.6 



10. 2 

 12. s 

 12. 2 

 12. 7 



d 10. 6 

 014.0 

 c "2.7 



2.6 

 8.2 



11. o 

 10. - 

 ■5- 3 

  7S 



(•) 

 22. 4 



89.8 

 90. o 

 97.1 

 91,3 

 89.8 

 '82. 7 



693.0 



&90.8 



96.6 



79.5 



96- 2 

 91.2 

 91.7 

 9O.9 

 88.3 



91.4 



97- o 



« Estimated. 



t* The 1920 record represents the combined production of the original and the second brood stocks. The penning together 

 of individuals of both stocks made it impossible to ascertain the production of either slock. 



c Decrease in production probably due to destruction of eggs by rats. 



d This record for males includes five Carolina original stock males used in hybridization studies 



e Records for production not obtained on account of storm which destroyed egg beds and washed many small and adult 

 terrapins from their inclosures. 



ORIGINAL CAROLINA BROOD STOCK. 



Considering the original or first lot of breeders it will be noted that highest egg 

 production occurred in 1915 and that since then the egg rate per female, with exactly 

 the same number of females laying, has diminished by from three to five eggs. The 

 percentage hatched has varied but slightly. This, however, would be reasonably 

 expected with the same number of males on hand and the number of eggs to be fertilized 

 somewhat less. In view of the fact that egg production has fallen off since the 1916 

 production and remained under that high mark now for four years through 1920, it 

 seems probable that the period of maximum egg production in this brood has passed. 

 However, the slight increase during 1918 and 1919 perhaps means that the brood 

 may still reach greater egg production than its maximum egg record of 1915. Still 

 beneath the maximum mark, it may also indicate that certain females are about to 

 reach maximum production while others have passed this point. The heavy falling off 

 in recorded egg production in 1920 (see figures for 1920 under second stock in Table 1) 

 was due to the depredations of rats which dug up many nests and destroyed hundreds 

 of eggs before control methods were effective. The 1920 figures, therefore, do not 

 represent the possible egg production and hatch, for the record of eggs laid would 

 doubtless have been very much higher had it not been for the destruction caused by 

 the rats. 



The average size of the females of this lot in 191 1 was 154 mm. 3 Considering what 

 is known of the history of some of the individuals of this lot since 1902, their size then 

 and their growth since, it appears probable that at the time of their measurement in 

 191 1 they averaged close to 20 years of age. The estimated age of these terrapins is 



3 Approximated from measurements recorded in inches. 



