DIAMOND-BACK TERRAPIN CULTURE 
29 
records for the original brood stock are rather obscure, but sufficient data are avail- 
able to show that only a small number of young was produced during the first years 
of confinement. Similar results (no definite figures are available) were obtained at 
a local terrapin farm and also for some wild terrapins purchased by the State of 
North Carolina and confined in 1925 for breeding purposes at the United States 
fisheries biological (Beaufort) station. The last-mentioned lot, consisting of 478 
females and 108 males, laid only 0.8 egg per female in 1925, 1.2 eggs in 1926, and 4.2 
in 1927. Another large increase was expected in 1928 but this, for reasons unknown, 
did not materialize, as the production of eggs remained the same as in 1927. 
The largest number of eggs laid per female by any group of terrapins that has 
been held in confinement during the course of the present experiments was produced 
by the first brood (1909) hatched and grown in captivity. In the first year few 
animals were hatched and only four females were grown to maturity. These four 
animals grew at a fairly uniform rate, and apparently all reached maturity at the 
same time. The rate of egg production was high and fairly constant, varying during 
the years 1915 to 1925, inclusive, from 22 to 34.3 eggs per female, with an average 
for the entire period of 29.4 eggs. The four females in this lot (used in certain dye 
feeding experiments in 1926, which proved fatal to two of them and sickened the 
others) appear to have been extremely fertile, and the rate of egg production far 
surpassed that of the later and larger broods. The broods of 1910 and 1911 prob- 
ably show to a far greater extent the rate of egg production that may be expected 
from terrapins grown in captivity. An increase in the average number of eggs laid 
per female for the lots is expected, as some of them have only recently reached sexual 
maturity. The tables show that a downward trend in egg production took place 
from 1919 to 1925 in the two lots of the 1910 brood and also for the winter-fed lot 
of the 1911 brood. A recovery is indicated for 1926 and a further one apparently 
will result for 1927, when all the young have been collected and counted. The 
general downward trend for these broods that took place, therefore, appears to have 
been only a “fluctuation,” which is shown also for the original wild brood stock. 
The data appear to indicate that certain years are not as productive of eggs as 
others. The tables show that egg production in 1921 and again in 1925 was lower 
than usual for nearly all the lots on hand. The causes for the “lean” years are not 
obvious. The care and the food received have not varied from year to year. In 
fact, the animals have remained in the immediate care of the same terrapin culturist 
throughout the course of the experiments. A study of the weather records kept at 
the station reveals nothing unusual during the lean years. On the other hand, the 
winters of 1917-18 and 1918-19 were both unusual, the first one having been extraor- 
dinarily cold and the second exceptionally mild, yet each of these winters was 
followed by a good laying season. The cause or causes of poor laying seasons remains 
for future investigation. 
The great variation in the number of eggs produced by individuals is referred 
to under the section of this report dealing with fertility, the range given for a single 
season being from 5 to 29 eggs. Experiments are under way whereby) it is hoped 
to determine whether certain females more or less constantly lay a small number 
of eggs while others produce a much larger number. These experiments have not 
been running long enough to yield definite results. The indications are, however, 
