182 PALEONTOLOGY 



or femoral end. It is less long and slender ; one border is 

 straight, the other concave, by the expansion toward that 

 border of the femoral end. Two shorter bones on each side 

 complete the pelvis below. One is of a simple form, straight, 

 thicker in proportion to its length than in the ilium : it may 

 be ischium. 



The other bone is shown, with its fellow, in t. xiii., fig. 6, 

 and xviii., figs. 8 and 9, of Von Meyer's treatise. That author 

 compares the pair of bones to the Aptyclius in shape ; they 

 may be the pubic bones. On this hypothesis, they are restored 

 to their true position at 64 (pubis) hi fig. 65. The femur (65) is 

 slightly expanded, and truncate at both ends ; it is not longer 

 than the ilium. The tibia (66) and fibula are separate bones, 

 like those of the fore-arm ; the margins, which are turned 

 toward each other, are most concave. They are rather more 

 than half the length of the femur. 



The foot-bones are separated by a fibro-cartilaginous tarsal 

 mass (68) from those of the leg. The form of the phalanges, 

 expanded and truncate at both ends, bespeaks their simple 

 ligamentous joints, and that they supported, like the fore-limb, 

 a fin or limb adapted simply for swimming. The argument 

 for the saurian affinities of Archegosaurus, based by V. Meyer 

 on the short fore-limbs of Mystriosaurus, already invalidated 

 by the difference of structure, is controverted by the fact, that 

 the hind limbs of Archegosaurus, like those of the Perenni- 

 branchs, are not only as simple in structure, but also as short, 

 as the fore-limbs. 



Genus Dendrerpeton. — In 1852 Sir Charles Lyell and Mr. 

 Dawson, in the course of their investigations of the coal strata 

 of Nova Scotia, remarkable for the erect fossil trees in certain 

 parts, discovered in the hollow of the trunk of one of these 

 trees (Sigillaria, 2 feet in diameter), which was wholly con- 

 verted into coal, some small bones, which Professor Wyman 

 of Boston surmised to have belonged to a batrachian reptile. 



