THE DIAMOND-BACK TERRAPIN. 



I03 



A conclusive statement of space requirement or of the value of extensive running 

 ground is not warranted from this single set of observations. It is of significance, how- 

 ever, that the greater growth has occurred in two successive years in the larger pool. 

 This may have been due, nevertheless, as much to the fact that the terrapins were 

 smaller in this pen than in the " close-confinement " pen and may have just reached or 

 were in a stage of rapid growth, whereas the other group may have passed that same 

 period. That plenty of space has a tendency to increase fecundity in the terrapin is 

 suggested by the 1909 brood. These terrapins, held in a pen 32 by 5 feet for six years, 

 have had a very large average yearly egg production per female. This pen provides 

 each terrapin with approximately 26.6 square feet of ground. The exceptionally high 

 laying record of these terrapins may be due, in part, to the large space and uncrowded 

 condition of their pen. Their size, of course, is large, but abundant space may be a 

 contributing factor in causing increased productiveness. 



1909 BROOD. 



This brood, the first terrapins hatched in captivity in the Beaufort pens considered 

 in this paper, consisted of 1 2 individuals — 8 males and 4 females. Several of the males 



MM. 

 ISO 



140 



130 

 120 



110 



100 



90 

 80 

 70 

 60 

 50 

 40 

 30 

 20 

 10 



1910 



1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 



FlG. 79- — Growth of 1909 brood of original Carolina brood stock. Ecs production and batch per female 

 per year expressed, respectively, by figures on the curve This brood has always had but four females. 

 Estimated. 



of this lot have been used in other experiments, and since [915 there have been only 2 

 males with the 4 females under observation. They have been kept during this time in a 

 small pen which, however, is large enough to support many more terrapins than these 6. 

 This 1909 lot has hibernated each winter since its birth and shows what is probably a 

 normal growth and development for terrapins held in captivity. The first eggs from the 

 females of this brood were laid in 1915 (fig. 79) when the terrapins were 6 years old. 

 The egg rate per female in that season was 24. Yearly since then there has been an 

 increase, until in 1919 the egg rate reached 32.2 per female. This 1919 egg production 

 was accompanied bv a hatch of 30 young per female and represented at that time the 

 best record observed at Beaufort for average egg production and hatch. In 1920, how- 



