262 



Bl'LLETIN OF THE BUREAU OF FISHERIES. 



with the river across the road, and on the, other with the ponds, so that the water 

 can be drawn into, or emptied from, each of them at will. 



All tlic ponds, whether large or small, are constructed very much on the same 

 plan. They are limited on their four sides by plank walls, the top of which may 

 either be on the level of the ground (see the right side of the section, cut '2) or may 

 lie more than a fool above the ground when two ponds are contiguous (the left side, 

 cut 2). Tn either case the plank wall has a cross plank of some width at right angles 

 to it on its to]), and is also buried some inches in the ground. The former arrange- 

 ment is. of course, to prevent the tortoises from climbing over the wall, and the latter 

 to prevent them from digging holes in the ground and making their escape in that 

 way. while at the same time it serves to exclude the moles. On the inner side of 

 the plank wall there is more or less of a level space, and then a downward incline of 



Cot. 2. — Section and plan <>f a turtle pond. 



3 or 4 feet. At the foot of this incline and directly around the water's edge there is 

 another level space which enables people to walk around the pond. From the edge 

 of the water the bottom of the pond deepens rather rapidly for a space of some 3 

 Eeet and there reaches the general level of the bottom, which is about 2 feet below 

 the level of the water. The greatest depth of a pond is about 3 feet and is always 

 toward the Watergate by which the pond communicates with the canals. The bottom 

 is of soft, dark mud, several inches thick, into which the tortoises are able to retire 

 to pass the winter. 



On a turtle farm one or more of the ponds is always reserved for large breeding 

 individuals, or "parents." as they are called. The just-hatched young or the first- 

 \ ear ones must have ponds of their own, as must also the second-\ r ear ones; those of 

 the third, fourth, and fifth years may be more or less mixed. 



