148 CHAPTERS ON THE NATURAL HISTORY 



habits; some of them I photographed in different attitudes, and 

 one of these (one about two-thirds grown) is presented as an illus- 

 tration here. Naturalists call this species Cistudo Carolina, being 

 one of the terrestrial representatives of the group. It is known 

 as a tortoise, a word probably derived from the old French term 

 tort is, twisted, referring to the apparent twist in its fore-limbs. 

 We usually call the aquatic forms turtles, and some of them 

 terrapins. The beautiful orange and black and brown markings 

 of our box-tortoise do not show in his picture, because they will 

 not take in an ordinary photograph. It requires a great deal of 

 patience to secure these photographs of living tortoises, because 

 the animal is frequently very unruly and hard to manage. Some 

 twenty-five or thirty years ago I collected an unusually fine speci- 

 men of this box-tortoise, that had a shell that was most beauti- 

 fully marked, and particularly perfect in form and other re- 

 spects. This shell I preserved and kept, and it is before me at 

 the present writing. Its superior, or dome-part, as stated above, 

 we call the carapace, while the breast-plate below, that has the 

 transverse hinge in it, is known as the plastron. These dorsal 

 and ventral shields that protect the entire body of the box-tor- 

 toise are joined at the sides by the lateral arches. Now the 

 carapace and plastron are overlaid by their hardened and brittle 

 plates. These belong to the skin-system, and so have been termed 

 epidermoid scutes. As has already been said, they are varie- 

 gated in color and in pattern in Cistudo, and have a definite ar- 

 rangement, as in other chelonians. Viewing our specimen from 

 above, it will be seen that there is a longitudinal row of these 

 plates, with a lateral row upon either side, and, finally, there is 

 a row of similar scutes all the way round the border. Upon the 

 plastron there is simply a double longitudinal row of much big- 

 ger plates. These epidermoid plates do not match, either in 

 form or arrangement, the bones of the true carapace and plas- 

 tron. To show this well, I have made drawings that I adapted 

 for the present purpose from figures given us by Dr. Gfinther, 

 formerly of the British Museum. They are shown below in Fig- 

 ures 40 and 41, and represent the carapace (Fig. 40) and the 

 plastron (Fig. 41) of Testudo pardulix. The first-named is 

 seen from above, and the latter is viewed upon its ventral sur- 

 face. The margins of the integumental scutes are indicated by 

 entire lines, while the sutures or borders of the bones of the os- 

 seous carapace are shown in dotted lines. Biologists for many 



