//*- 



LEAVES FROM THE NOTE-BOOK OF A NATURALIST. 



79 



length. The true lungs begin to be formed ; and, 

 as they advance, the internal gills are gradually 

 obliterated. Thus the whole circulation is altered, 

 and the young frog quits the water, exchanging 

 its entirely aquatic and herbivorous life for a car- 

 nivorous, and, for the most part, terrestrial exist- 

 ence. These metamorphoses, which rfval those 

 of the insects, may bs seen on a grander scale in 

 the Eana paradoxa. 



The serpents have two auricles, but the batr?,- 

 chians have, strictly speaking, only one, but it is 

 separated in'ernally into two chambers. 



One worjr: more on the discrepancies of reptile 

 organization, and we will cease to pursue an in- 

 quiry which would be followed out with more 

 aptitude in a work more conversant with compara- 

 tive anatomy than this can pretend to be ; but the 

 general reader, as well as the student, should keep 

 those discrepancies steadily in view. The obser- 

 vations, however, shall be confined to the varying 

 skeletons. 



Take the cranium of a crocodile. A more 

 solid, bony mass, you could hardly see. Now 

 turn to that of a boa. The skull, you see, is 

 made up of a considerable number of pieces, all 

 admirably fitted and joined together, but with such 

 an adaptation as easily to admit of separation. 

 Why is this ? The long head and widely exten- 

 sive jaws of the crocodile enable it to secure and 

 take into the stomach a comparatively large prey. 

 But the serpent frequently has to master and swal- 

 low an animal utterly disproportioned to the usual 

 gape of the mouth ; the skull is, therefore, so 

 framed as easily to admit of partial dislocation, so 

 that it may aid the dilatation of the jaws and 

 throat, and facilitate deglutition. The ribs in the 

 frogs, as before observed, are almost null ; in the 

 serpents they are so lavishly developed and so 

 freely articulated that they i re used as organs of 

 motion. In the tortoises tl iy are implanted and 

 incorporated with the rest ( '. the canapace. The 

 ribs of the serpent ma? V- compared to the legs 

 of a millipede situa'e'l internally, and operating 

 externally principp'Jy by acting on the scutes of 

 the belly on which it creeps. Some reptiles have 

 not only a trnr breast-bone, but also an addition, 

 which has Leon termed an abdominal sternum. 

 This may be seen in the crocodiles, and seems to 

 be produced !>y the ossification of the tendons of 

 the recti muscles. But while some have two 

 sterna, others have none at all. The chameleon, 

 for instance, though the ribs are well formed, has 

 no breast-bone. The tortoise, and the majority of 

 saurians, are gifted with four sufficiently well- 

 developed extremities. Chirotes and bipes have 

 only two ; the former an anterior pair, the latter 

 a posterior pair, and those but poorly framed. 



But though these and other great differences of 

 organization are patem among the reptiles, every 

 bone of every reptile is marked with such pecu- 

 liarity of character as to indicate at once the clas; 

 to which it belongs. A skilful comparative anat- 

 omist can never mistake such a bone for that of 

 any other race of animals. Professor Owen and 



other palaeontologists have largely profited by 

 their knowledge of this peculiarity, as appears 

 from the great and admirable work on British fossil 

 reptiles by the professor, now in the course of 

 publication.* 



From the great difference in the organization 

 of this class, a great variety of motility was to be 

 xpected : 



The motion of reptiles is as various as their 

 structure, and exhibits a great diversity, particu- 

 larly in the modes of progression. The slow 

 march of the land tortoises, the paddling of the tur- 

 tles, the swimming and walking of the crocodiles, 

 the newts, and the protei, the agility of the lizards, 

 the rapid serpentine advance of the snakes, the 

 leaping of the frogs, offer a widely-extended scale 

 of motion. If we add the vaulting of the dragons, 

 and the flying of the pterodactyles, there is hardly 

 any mode of animal progression which is not to be 

 found among the reptiles. f 



When we examine the different systems pub- 

 lished by zoologists with reference to the reptiles, 

 we find, with few exceptions, the first place as- 

 signed to the chelonians or tortoises ; and, before 

 we proceed to notice the other forms, let us rapid- 

 ly survey this highly-interesting order. 



The land-tortoises first claim attention. 



28th July. I went to see the great tortoise 

 (Testudo elephantopus) presented by the queen to 

 the Zoological Society of London, and arrived at 

 the garden in the Regent's Park between nine and 

 ten o'clock. The morning had been rainy, but 

 the sun bravely struggled through the clouds 

 which cleared away before his radiant presence, 

 as the story-book has it, and I saw the venerable 

 reptile in its paddock before the newly-erected hut 

 built for its reception near the otters' pond. It is 

 the largest I ever beheld. The ancient seemed to 

 be in a dreamy kind of doze, -with its head tucked 

 into its shell, which glittered still moist with 

 the rain that had fallen in the sunbeams a shell 

 fit to make a lyre for Polypheme, if he had been 

 inclined to try his hand when tired of the hundred 

 reeds of decent growth that made a pipe for his 

 capacious mouth. Though the weather had been 

 very wet since its arrival a day or two previously, 

 it did not seem to have availed itself of the shelter 

 of its hut. Another comparatively small land- 

 tortoise was also in the enclosure near a corner, 

 but entirely exposed to the weather. One colos- 

 sal anterior foot of the dozing giant rested on its 

 sole ; its fellow was carelessly lying on its side. 

 The soles of both the hind feet were on the turf. 

 I scratched the sole of the anterior foot, which 

 was exposed, and then the head. The sleeper 

 was awakened, and put forth its long, serpentine 

 neck, opened one eye very deliberately, and then 

 the other as lazily, gave a gasp or two, withdrew 

 the head, and then again protruded it. Cabbages, 

 lettuces, and vegetable marrows, the latter equal- 

 ling in tempting appearance those which the mad 



* A History of British Fossil Reptiles. By Richard 

 Owen, F.R.S., &c. 4to. London: Printed for the Au- 

 thor. 



t Penny Cyclopedia, vol. xix., p. 410. 



