REPTILES. 



left I'ubclavian vein ; where they join behind tlie aorta, and 

 form a number of branches, which are afterwards joined by 

 the lymphatics of tiie left lide of the neck : fo that here a 

 net-work or plexus is formed, as upon the right fide. 

 From this plexus a branch idues, which opens into the angle 

 between the jugular and the lower part or trunk of the 

 fubclavian vein. In thefe net-works, formed by the lym- 

 phatics near their termination in the veins, this fyftem in 

 the turtle differs remarkably from that in birds. Hewfon's 

 Account of the Lymphatic Syftem in Amphibious Animals, 

 Philof. Tranf. vol. 69. p. 198. 



The Liver, which is divided in the mammalia into feveral 

 lobes diftinft from each other, and is more uniform ni birds, 

 is ftill lefs divided in reptiles. Often it has no divilion of 

 lobes, but is merely irregularly fiffured on its loole and 

 thin edge. Its proportionate fize, however, is more confi- 

 derable than in the two clades jult mentioned. Occupying 

 ufually the two hypochondria, it extends far backwards 

 under the inteftines, and is fupported in its pofition by 

 folds of the peritoneum, analogous to thofe which cxiil in 

 the mammalia. Its colour is no longer that reddifli-brown 

 which is feen in the mammalia and birds ; but it partakes 

 more of yellow. 



In the chelonians the liver exhibits a peculiar arrangement, 

 being divided into two rounded irregular mafles, of which 

 the right occupies the fame hypochondrium, and the other 

 is conne<3:ed to the fmall curvature of the (lomach. They 

 are united by two narrow produftions of the fame fubftance, 

 in which the principal vefTels pafs. In the green lizard, 

 the geckos, the dragons, the iguanas, it forms a fingle mafs 

 of various figure, flat or convex below, concave above. 

 Its loofe edge has two filTures in the dragon, dividing it 

 into three lobes, of which the right is prolonged into a fort 

 of tail. There is only one fidure in the geckos, and the 

 right part is equally more extenfive than the left. In the 

 common iguana it is lengthened into a long appendix. In 

 the crocodile and cameleon the liver has two very diftinft 

 lobes ; and moreover, in the latter, a long appendix. It 

 has only one lobe in the ferpents, in whom it is long and 

 cylindrical. Like other organs, it afTumes in this order a 

 figure correfponding to the elongated form of their bodies. 

 There is one lobe only in the falamanders, but two in the 

 other batracians. 



Hepatic Canals. — The common trunk of thefe canals is 

 ufually feparate from the cyftic duft, and not inferted with 

 the latter in the intellinal canal, in reptiles, as well as in 

 birds. This has been obferved in the chelonian and fau- 

 rian orders, in feveral ophidians, and fome batracians. Yet 

 this arrangement is not conftant. For, in the crocodile, 

 where the hepatic is fometimes feparate from the cyftic 

 duft, it fends at other times a branch to the gall-bladder, 

 which is inferted a little above its neck, and is itfelf united 

 to the cyftic canal, not far from the inteftine. The mouth 

 of the common canal was diftant from the pylorus, fays 

 Cuvier, 0.26 in a crocodile, whofe whole inteftiaal canal 

 was rather more than a metre (about 39, inches) in length. 



In the teftudo graeca the hepatic canal fends a branch of 

 communication to the cyftic canal, not far from the gall- 

 bladder ; but thefe two canals open feparately into the in- 

 teftine, though near each other ; the former before the latter. 

 The Gall Bladder has its fundus ufually directed back- 

 wards. Its proportional volume is lefs confiderable than 

 in mammalia and birds ; and it is more intimately connefted 

 with the liver than in thefe claffes. In the teftudines it is 

 almoft entirely concealed in the right lobe of the vifcus ; 

 and is placed under the fame lobe in the crocodile. Where 

 the liver is not divided into lobes, the fituation of this refer- 

 VoL. XXIX. 



voir is marked out by a fifl'ure. In the ophidians the gall- 

 bladder is abfolulcly feparated from the liver, and fituated 

 at the fide of the ftomach, near the pylorus, a ftiort diftance 

 beyond the pollerior extremity of that vifcus. Its form 

 is generally oval, but it approaches to the cylindrical figure 

 in the iguana. 



The connexions of the cydic and hepatic canals hare 

 been already mentioned. The former remains generally 

 didinft from the latter, by the fide of which it is inlerted 

 into the inteftine. Sometimes it receives the branches of 

 the latter in fuccedion. 



The Pancreas is a conglomerate gland, as in mammalia 

 and birds, and podcdes the fame ilrufture fv/itli fome un- 

 important modifications of colour, conllftence, lobular divi- 

 fions, &c.) as in man. Its pofition and figure vary in rep- 

 tiles. In feveral ciielonians it is triangular. That of the 

 Nilotic crocodile is divided into lobes : it is irregular in the 

 ophidians, and fituated on the right of the origin of the 

 intellinal canal. In the frog its figure is equally irregular, 

 and it is fituated in the arc formed by the (lomach towards 

 the front. It is placed in the firft curve of the inteftine in 

 the falamander. 



There is either a fingle or double pancreatic canal. In 

 the Nilotic crocodile, for example, there are two, inferted io 

 the inteftine after the biliary canals, while there is only one 

 in the land falamander, the infertion of which precedes that 

 of the biliary tubes. 



The Spleen. — This is a vifcus, of which the ufe is not 

 hitherto underttood. It cxiils in all the vertebral animals ; 

 but its importance feems to diminidi as we pafs from mam- 

 malia to birds, from the latter to reptiles, and from thefe 

 again to fifties ; at leaft, if we may judge from the fuccelfivc 

 diminution of its volume in thefe four clades. 



Its figure varies confiderably in this clafs. It is diaped 

 like the kidney in the teftudines ; fmall and fphericalii the 

 frogs and toads ; elongated in the falamanders, as wellas in 

 the faurian and ophidian orders. 



The abdominal Cavity, Peritoneum, and its Procejfes The 



offices of this membrane, in covering and infulating the 

 various vifcera, confining them, by its continuations and 

 folds, more or lefs clofely to the fides of the cavity, and 

 facilitating, by its fmooth furface, their motions with rcfpeft 

 to each other, and to the containing cavity, will convince us 

 of the importance of the membrane, and lead us to expeft 

 that it ftiould exift very generally. We, confequently, 

 find it in all the vertebral animals. Generally white, deli- 

 cate, and tranfparent, it is fometimes black in reptiles. 



In this clafs, as in birds, there is no diaphragm, and con- 

 fequently no diftindion of abdominal and thoracic cavities. 

 All the vifcera are contained in one large cavity, and fur- 

 rounded by one membrane. Geoffroy, however, deferibes 

 fome mufcular fibres coming from the fternum, and fixed 

 to a membrane covering the convexity of the hver, which 

 feem hke the rudiment of a diaphragm. Annales du Mu- 

 feum, V. ii. p. 50. 



In the chelonians, the membrane produces certain fubdi- 

 vifions of the common cavity of the thorax and abdomen. 

 We remark, 1 ft, the cavity of the lungs, which are coni 

 tinued far backwards, above tiie heart, liver, and inteftines ; 

 2dly, that of the heart, or pericardium, which touches the 

 following behind ; 3dly, that of the abdominal vifcera, con- 

 taining the ftomaeh, liver, inteftines, ovaries, tefticles, and 

 urinary bladder. In front it covers the liver, forming a fort 

 of membranous diaphragm, feparating it from the heart ; 

 and it clofes the cavity of the pelvis behind. It alfo fur- 

 nifties the mefenteric folds. The texture of this membrane 

 appears ftronger in the teftudines than in other reptiles. 



4Z The 



