THE DIAMOND-BACK TERRAPIN. 



99 



distance from the stove contain the smallest. This indicates the desirability of having 

 a heating system which radiates its warmth equally and in constant and considerable 

 quantity. To the commercial culturist a heating system of this kind is of prime necessity. 

 The effect of winter feeding other than in its bearing on actual growth — that is, in causing 

 earlier arrival at sexual maturity — will be indicated in certain of the annual brood 

 studies. This is another valuable consideration for the commercial grower of terrapins. 

 What growth may be expected of winter-fed terrapins, compared with those that 

 are allowed to hibernate, is well suggested in the records of the 19 10 and 191 1 broods, 

 lots of which received these treatments, respectively. The fed lots at any age are 

 generally about 1 year's growth in advance of the hibernating lots, and in some cases 

 much more. This difference in growth in 2 and 3 year old terrapins is from about 

 10 to 20 mm. The difference between the average lengths of the lots diminishes as 

 they pass the fourth year. From this time on the variation averages about 10 mm. 

 and remains thus constant through the ninth year, if not longer (Table 3, fig. 77). 



Tabu; 3. — Growth op Winter-fed Versis Hibernated Terrapins. 



Age 



Season ul measurement 



/Spring. 



\Fall.... 



/Spring. 



\Fail.... 

 Do.. 



/Spring. . 



\Fall... 



Do 



Do .. 



Do 



Do 



Do 



i9ioand 191 1 broods combined. 



Winter-led. 



Number. 



97 

 95 

 "5 



183 

 183 



81 

 309 

 ■3* 



301 

 136 



Measurement in 

 millimeters. 



Total. Average. 



" 3. 006 



4. 407 

 7.O07 

 14. 393 

 16. 667 



9. 31 S 

 26, 556 

 '7. 277 



29, 693 

 17.984 



137 



■30. 



14a 



a' 



Hibernated. 



Number. 



98 

 89 



190 

 r83 



175 

 78 

 168 

 ■67 

 r;6 

 167 

 89 



Measurement in 

 millimeters. 



Total. 



o 3. 738 

 3.833 

 7.980 

 10. 976 



rs. 807 

 8. 360 



19, 4S0 

 30, 560 



20. 347 

 22. 7S7 

 12. 147 



Average. 



37.9 

 43° 

 43. o 

 6a 3 



90.3 

 105.8 

 115.9 

 121 1 

 130.4 

 136.3 

 ■36 4 



a Measurement of plastrons. 



MM. 



150 



140 



130 



120 



110 



100 



90 



80 



70 



60 



50 



40 



30 



20 



10 



YfAR 



I N. 

 6 



Flo. 77. — Average growth of winter-fed and hibernated terrapins, 

 and hibernated lots of the 1910 and 1911 broods. 



Curves based on combined records of growth of winter-fed 

 , Winter-fed; hibernated. 



