REPTILES. 



the ifchium is turned backward and downward, and forms 

 the real oUcoiis circle of tlic pelvis. This conformation is 

 fo fingular, that the parts of the pelvis of the turtle, when 

 the whole is viewed out of its natural pofition, may very 

 eafdy be millaken for one another ; for the pubis rcfemblcs 

 the ilium, the ifchium the pubis, and the ilium tlie ifchium. 

 There is, befides, another very remarkable peculiarity in 

 the pelvis of tortoifes ; the ilium, and confequently the 

 whole mafs of the pelvis with which that bone is united, is 

 moveable on the vertebral column. 



In the crocodile, and in the tupinambis, the difpofition of 

 the pelvis has a great refemblance to tliat of the tortoife. 

 In the crocodile the pubis receives the ventral ribs. In the 

 cameleon and the iguana it is narrow, and the bones of the 

 ifchium form, by this union, a projedting crcit. In the 

 frog, and in the Surinam and common toads, the oll'a ilii 

 are much elongated ; the pubis and the ifchium are (hort, 

 and united in a fingle folid piece, the fyniphifis of which 

 forms a creft, more or lefs round. In the falamandcr, the 

 conformation is precifely the fame. The oila ilii are narrow, 

 and almoll cylindrical ; and the olTa pubis completely united 

 with the ifchium, form only a large bony plate without 

 any hole. 



Thigh- Bone The femur of oviparous quadrupeds re- 



fembles that of other animals ; it has, however, a double 

 curvature, more or lefs evident. In front it prefents a 

 convexity towards the tibial extremity, and a conca- 

 vity near the pelvis. In the tortoife the trochanters are 

 well defined, but they are not to be found in the lizards 

 and frogs. The figure of the femur is in general round, 

 except in the Surinam toad, in which it is very flat. 



Bones of the Leg. — Oviparous quadrupeds have the tibia 

 and fibula diitindl and feparated from each other through- 

 out their whole length. Thefe two bones are nearly of 

 the fame magnitude in the tortoifes and lizards. The 

 frog has but one bone, but a furrow feems to indicate the 

 union of the tibia and fibula. In thefe animals the tibia 

 and fibula are, for the moil part, direftly articulated to the 

 thigh-bone. 



Bones of the Ankle. — The allragalus is articulated to the 

 tibia, and the os calcis to the fibula in all reptiles. The 

 tarfns of the crocodile has five bones, vi-z,. an aitragalus, 

 an OS calcis, two cuneiformia, anfwering to the two middle 

 metatarfal bones, and one out of the range, which anfwers 

 to the external metatarfal bone. There are four metatarfal 

 bones. The bone fituated without the range ferves to 

 fupport the httle toe in the mud tortoife. In the fea tor- 

 toife it is very flat. The os calcis and aftragalus are very 

 fmall. In frogs, the allragalus and os calcis are v^ry long, 

 and might at firll fight be taken for the tibia and fibula, if 

 they did not form the third joint of the pofterior extremity. 

 There are on the fore part, four little cuneiform, five meta- 

 tarfal bones, and one in the form of a hook, which is very 

 minute. Thefe are fimilar in the Surinam and common 

 toad. 



Bones of the Toes. — The number of the toes varies much 

 in reptiles ; as may be feen from the following table. 



Number of the phalanges of the toes of reptiles, exclu- 

 five of the metatarfal bones, beginning at the poUex, or in- 

 ternal toe. 



Crocodile - - - 2, 3, 4, 4. 



Lizard - - - 2, 3, 4, 5, 4. 



Cimeleon - - - 3j 3> 4. 4> 3- 



Salamander - - 2, 3, 3, 3. 



Sea tortoile - -2,3, 3, 4, 2. 



Mud tortoife - - 2, 3, 3, 3, 2. 



Frog . . . I, 2, 2, 3, 4, 3. 



The iaurians prefent us with arrangements in their ex- 

 tremities, not met with in any of the mammaha. We 

 have Ipecies podefTing only fore-limbs, or only hind-limbs ; 

 others with tour limbs, and one toe only on eacli ; and 

 other unufual combinations in the iiumi)cr of toes on the 

 fore and hind-limbs. Thefe circumllances are noticed in 

 tiiofe lizards which approach to the form of ferpents, and 

 whofe Imall imperfcdt limbs feem more like rudiments than 

 complete members, ferving as intermediate links between 

 the faurian and ophidian orders. See Laccpede in the 

 Ann. du Mufeum, ii. p. 351, with figures of a lezard mo- 

 nodactyle, and tetradaclyle ; and Daudin in his Hill. Nat. 

 des Reptiles, vol. iv. in the hillory of the genera Seps 

 andChalcide. We know nothing, however, about the ofte- 

 ology of thefe — we might almoll fay — ridiculous limbs, 

 they are fo obvioufly inadequate to the purpofe of loco- 

 motion. 



Of the Mufcles. 



Mufiles of the Spine. — There are few Ipiual mufcles in froffS. 

 The mufcle which is analogous to the ifchio-coccygeus is 

 large and thin, and occupies all the fpaee comprifcd be- 

 tween the long bone of the coccyx and the ilia. Its fibres 

 are oblique, and it ferves to draw the coccyx into the di- 

 reftiou of the fpine. That which is analogous to the 

 lumbo-coilalis, ariies above the lall by a fort of point at- 

 tached to the coccyx. It extends quite to the head, into 

 which it is infcrted, and detaches fibres in its progrefs to 

 each of the tranfverfe procefles, which form a kind of in- 

 terfeftion upon its furface. The obliquus fuperior arifes 

 from the head at the margin of the foramen magnum, and 

 is infertcd into the tranfverfe procefles ot the firll dorfal 

 vertebra. There is only one fmall reftus anterior, it 

 arifes from the bafe of the cranium, below the foramen 

 magnum, and is inferted into the firtl of the tranfverfe pro- 

 ceffes. The intcr-tranfverfales are like the human. The 

 fpinal mufcles of the falamander much refemble thofe of 

 the frog ; thofe of the tail are very fimilar to the muicles 

 of fifhes. The fpine of the tortoife has no motion except 

 in the parts belonging to the neck and tail. Thofe of the 

 back and loins, which are oflified together, have no mufcles. 

 The mufcles of the neck are very different from thofe of 

 man. The motions they produce are thofe of elongation, 

 by which the head is protruded from the (hell ; and thofe 

 of retraclion, by which it is withdrawn, the neck being 

 bent in the form of a Z. The firll of the mufcles proper 

 to the neck is attached to the under part of the anterior 

 lateral border of the back-fliell, and into the tranfverfe 

 procefs of the firil vertebra ; it raifes the neck and draws 

 it back. Another proceeds from the anterior and middle 

 part of the fhell : it is inferted by four flefhy lips, which 

 are feparate throughout a confiderable portion of their 

 extent, into the articular proceffes of the third, fourth, 

 fifth, and fixth vertebrae of the neck. It draws the neck 

 back when the head is much extended, and pulhes it out 

 when it is retradled. A mufcle alfo arifes from the arti- 

 cular procefles of the third, fourth, and fifth vertebrx of 

 the neck, by three flefhy portions that afterwards unite, 

 and terminate in two tendons ; one of which is inferted 

 into the tranverfe procefs of the firil, and the other into 

 the fpinous procefs of the fecond vertebra. This mufcle 

 bends the neck upon itlelf, making it defcribe a curve, 

 which is convex downwards ; this motion brings the head 

 under the fliell. A mufcle analogous to the longus colli 

 arifes from the under part of the body of the fecond dorfal 

 vertebra, beneath the fhell ; it afcends along the neck, and 

 furnilhes aponeurotic flips to al the trnnfverfe procefles, 



6 as 



