196 FOSSIL TESTUDINATA. 



ready means of escape by flight or concealment from 

 their enemies. We learn from Geology that this Order be- 

 gan to exist nearly at the same time with the Order of Sau- 

 rians, and has continued co-extensively with them through 

 the secondary and tertiary formations, unto the present time: 

 their fossil remains present also the same threefold divisions 

 that exist among modern Testudinata, into groups re- 

 spectively adapted to live in salt and fresh-water, and upon 

 the land. 



Animals of this Order have yet been found only in strata 

 more recent than the carboniferous series.* The earliest 

 example recorded by Cuvier, (Oss. Foss. Vol. 5, Pt. 2, p. 

 525,) is that of a very large species of Sea Turtle, the shell 

 of which was eight feet long, occurring in the Muschelkalk 

 at Luneville. Another Marine species has been found at 

 Glaris, in slate referable to the lower cretaceous formation. 

 A third occurs in the upper cretaceous freestone at Maes- 

 tricht. All these are associated with the remains of other 

 animals that are marine ; and though they differ both from 

 living Turtles and from one another, they still exhibit such 

 general accordance in the principles of their construction, 

 with the conditions by which existing Turtles are fitted for 

 their marine abode, that Cuvier was at once enabled to pro- 

 nounce these fossil species to have been indubitably inha- 

 bitants of the sea.f 



* The fragment from the Caithness slate, engraved in the Gaol. Trans. 

 Lond. V. iii. PI. 16, Fig. 6, as portions of a trionyx, is pronounced by M. 

 Agassiz to be part of a fisli. 



t Plate 25', Fig, 4, represents a Turtle from tlie slate of Glaris : it is 

 shown to have been marine by tlie unequal elongation of the toes in the 

 anterior paddle; because, in fresh-water Tortoises, all tlie toes are nearly 

 equal, and of moderate length ; and in land Tortoises, they are also 

 nearly equal, and short ; but in all marine species they are very long, 

 and the central toe of the anterior paddle, is by much the longest of all. 

 The accordance with this latter condition in the specimen before us, is 

 at once apparent ; and both in tiiis respect and general structure, it ap- 

 proaches very nearly to living genera. This figure is copied from VoK 



