CHELONIA. 



CHELONIA. 





more cruel in appearance than in reality. Most are familiar with the 

 length of time that a turtle will move after its head is off, and the 

 snap of the jaws which the severed head will give ; but there is 

 reason for l>elieviug that there is more of irritability than sensation 

 in such motions ; and the state of Redi's tortoises must have been 

 analogous. 



Redi, in the beginning of November, made a large opening in the 

 skull of a Land-Tortoise, extracted the brain, and cleaned out the 

 cavity. He then set the animal at liberty, and it groped its way 

 freely about wherever it pleased, as if it had not been injured. Redi 

 makes use of the term 'groping' (brancolando), because he says that 

 when the tortoise was deprived of its brain it closed its eyes, which 

 it never again opened. The wound which was left open skinned over 

 in three days, and the tortoise, continuing to go about and execute 

 other movements, lived to the middle of May. On a post-mortem 

 examination the cavity which the brain had occupied was found empty 

 and clean, with the exception of a small dry and black clot of blood. 

 He repeated this experiment upon many other Land-Tortoises in the 

 months of November, January, February, and March, with this differ- 

 ence, that some were locomotive at their pleasure, whilst others, 

 though they made other motions, did not move about : he found the 

 same results when he treated Fresh-Water Tortoises in the same 

 manner, but they did not live so long as the terrestrial species. He 

 states his belief that the Marine Tortoises would live a long time 

 without their brain, for he received a turtle which he treated in the 

 game way, and though it was much spent and faint from having been 

 long out of the sea, it lived six days. In November he deprived a 

 large tortoise of its head, without which it continued to live twenty- 

 three days : it did not move about as those did whose brain had been 

 taken out, but when its fore or hind legs were pricked or poked, it 

 drew them up with great strength, and executed many other move- 

 ments. To assure himself beyond all doubt that life, such as it was, 

 continued in such cases, he cut off the heads of four other tortoises, 

 and on opening two, twelve days afterwards, he saw the heart beat 

 and the blood enter and leave it. 



We have already had occasion to call attention to the great length 

 of time during which these reptiles will live without food, and the 

 fact* above recorded afford additional proof of their extreme tenacity 

 of life. 



Touch. In the greater part of this order, skin, properly so called, 

 does not exist at all on certain parts of the body, or is reduced to a 

 delicate fibrous plate applied like a simple periosteum on the bones 

 of the head and on the external parts of the vertebrae of the back, 

 the ribs, and sternum. The Soft Tortoises (Trionyx and kpliargis, for 

 instance) are the only ones that differ in this respect. Nevertheless 

 the neck, the feet, and most frequently a considerable part of the tail, 

 are covered with a true flexible skin. This skin in the Matamata is 

 fringed, or furnished with moveable appendages on the lateral parts of 

 the head and neck. There can be no doubt that the sort of touch or 

 sensation which will indicate to a Trionyjr, or even to a Marine or 

 Land-Tortoise, the differences of temperature that affect the medium 

 wherein it moves, is present in those animals, but the sensibility of a 

 true touch must be very much blunted in them. Some have their toes 

 united down to the nails, or rather hoofs, and absolutely immoveable ; 

 others have them flattened, and forming a sort of paddle, as in C'lielone 

 and Sphartfis ; or the whole foot terminates by a sort of shapeless 

 stump, rounded like that of the elephant, the presence of the toes 

 being only indicated by those nails or hoofs, as in the Land-Tortoises. 

 Others, it is true, Emy, Trionys, and Chelyt, for example, have their 

 toes very distinct, but they are nevertheless united by membranes, 

 and in general their feet seem more adapted for the different modes 

 of transport than for touch. The Matamata indeed has its nose 

 prolonged into a sort of moveable proboscis ; but this organisation 

 seems to be directed more to favour the required mode of respiration, 

 than to give the animal that sort of perception exercised by the 

 snniit of swine and the muzzles of moles and some shrews. (Dume'ril 

 and liibron.) 



Taste. The wide fleshy tongue, with iU distinct papilUe, like those 

 of Mammals, seems well calculated for tasting vegetable and animal 

 juices after the food is minced up by the horny mandibles ; the fleshy 

 lip* nn the outside of these mandibles in the Trionycet probably assist 

 in retaining these juices. 



Smell. Though there is probably sufficient of this sense to assist 

 the animal in its discrimination of food, and aid the functions of the 

 tongue in giving the animal a perception of flavour, it may be con- 

 < luili-fl from the very simple state of the organs, so different from the 

 complication of those in animals where the sense is known to be 

 highly developed, that it is not very acute in the tortoises. 



Hearing. From the structure of the internal ear, to which we 

 have before alluded, it might be inferred that this function is tolerably 

 acute, but many of the species appear very insensible to sound. 



Sight. The eye is well developed and is large. It is modified so 

 aa to be adapted to the medium, whether air or water, through which 

 the light is to be transmitted. In the substance of the cornea scales 

 or osseous plates are found analogous to those in birds, and there are 

 three eyelids and two lachrymal glands. 



Reproduction. According to the accounts of voyagers the Coriaceous 

 Tortoises (Upkargii) and the Trwnycet seern to pair, and two inclivi- 



JCAT. BIST. DIV. VOL. I. 



duals of different sexes remain constantly together in the same places. 

 The great Marine Tortoises, as is well known, come every year at their 

 appointed times to deposit their eggs in the sand on the shores of the 

 sea and banks of rivers near strands of gentle declivity. There the 

 females hollow out a sort of rude but strong vaulted nest or oven, as 

 it may be termed, wherein the eggs may have the benefit of the con- 

 centrated rays of the sun, so as to enjoy an equable heat, as in the 

 case of eggs under a sitting hen, but under circumstances which do 

 not permit the body of the mother to impart the necessary warmth. 

 The shell of these eggs is generally solid, and their form globular, or 

 of a short cylindrical shape equally rounded at the extremities. A 

 female Turtle will lay as many as a hundred at onetime. The plastron 

 of the males of many species of Chelonia is concave, that of the females 

 being convex. Messrs. Dume'ril and Bibron say that in the Qhelonians 

 and Anourous Batrachians from eighteen to thirty -one days and more 

 have elapsed before the male has quitted the female. 



With regard to the integument of the carapace and plastron, the 

 number, colour, and shape of the investing plates of horn or shell, 

 as it is termed, vary considerably. The subjoined cuts will convey a 

 better notion than words of their arrangement in a laud and marine 

 species ; but it must be considered that these are mere examples, and 

 that the variety is very great. 



Carapace of Teatudo maryinata, 

 covered with shell. 



Carapace of Chelone Cm/mina, 

 covered with shell. 



Systematic Arrangement and Natural Hutory. 



Aristotle has mentioned three principal groups of Tortoises, or at 

 any rate genera, under the names of XeAiur) x(p<raia for the Land- 

 Tortoise ; XeAconj flaAarria or 0aAa<r<n'a for the Sea-Tortoise or Turtle 

 (' Hist. Aniin.. ii. 17) ; and 'E^ifj for the Fresh-Water Tortoise (Ibid., 

 v. 33). Gesner remarks that there are three "sumnm genera" of 

 Tortoises : the 1st, terrestrial ; the 2nd, living in fresh-waters ; and 

 the 3rd, in the waters of the sea. Messrs. Dume'ril and Bibron copy 

 his ' Corallarium de Testudinibus in Genere,' to show how far it 

 accords with their own arrangement, as follows : 



Teitudo 

 aut est 



terretri CTestudo marina, 



j 6a\arria. 

 ' mari | Mua marinus, Miis fl 



l_ Tioy. 



iii/uatic, aut in ("puriore, ut lacubus, 



aqu.1 clulci < amnibus. 



[ cajnosa, ut paludibus. 



Linnaeus placed the form at the head of his Amphibia Reptilia, 

 under the generic name Tmtudo. 



Cuvier divides them into five sub-genera : 1, the Land-Tortoises 

 (Ttitudo, Brongn.); 2, the Fresh-Water Tortoises ,(Emys, Brongn.), 

 including the Box-Tortoises (Ttrrapene, Merrem ; Kinoatemm, Spix ; 

 Cittudo, Fleming) ; 3, the Marine Tortoises ; 4, the Chelydes (Teatudo 

 fimbriota) ; 5, the Soft Tortoises (Trionyj; Geoff.). 



Dr. J. E. Gray, in his ' Catalogue of the Tortoises, Crocodiles, and 

 Amphisbaenians, in the Collection of the British Museum,' 1844, makes 

 the Chelonia, the third order of Reptiles in his arrangement, come 

 under his second section, Cataphracta, the Squamata- being the first. 



Family 1. Tetu,dinid<z. 

 Genera : Tetludo. Clurnna. Kinixyi. Pyj-iji. 



Family 2. Emydidue. 



Genera : Geoemyda. Emys. Cyclemyn. Malaclemyt. Ciiludo. 

 Kinoittrnon. Ckelydra. Platyiternum. 



Family 3. Chelydida. 



QeneT&'.Sternollterut. Pelomeduea. Jlydraspis. Chelymyi. Phryn- 

 opt. Chelodina. Ilydromeduta. Cltelys. Peltocephalua. Podocnemit. 



Family 4. Trionycidce. 

 Genera : Triomyjc. Emyda. 



Family 5. Cheloniadte. 

 Genera : Sphargit. Chelonia. Caretta. Caouana. 



Messrs. Dume'ril and Bibron, in their elaborate and highly valuable- 

 ' Erpe'tologie,' divide the Tortoises, or Chelonians, into the following 



8 a 



