Vu PECTORAL FINS 243 
(Fig. 146, G) is uniserial, closely resembling that of the more 
typical Elasmobranchs.' There are three basal elements, a pro- 
pterygium, a mesopterygium, and a metapterygium, each of 
which supports a series of partially ossified radialia. Little is 
Fic. 146.—Pectoral fins of various Fishes. A, Acanthias vulgaris; B, Raia sp. ; 
C, Chimaera monstrosa ; D, Acipenser rhynchaeus ; E, Amia calva ; F, Lepidosteus 
platyrhynchus ; G, Polypterus bichir ; H, Salmo salvelinus. The preaxial side of 
each fin is to the left and the postaxial to the right. 7, Dermal fin-ray ; ms, 
mesopterygium ; mt, metapterygium ; p, propterygium ; 7, free radialia; 1, 5, the 
preaxial and postaxial basal elements in a Teleost, which may be mesopterygial and 
metapterygial pieces respectively, the three remaining basal pieces probably being 
intrusive metapterygial radialia directly articulating with the pectoral girdle. In 
B, D, E, and F, similar intrusive radialia‘are shown. (From Gegenbaur.) 
known of the endoskeletal elements of the broadly or acutely 
lobate fins of the fossil Crossopterygii, but it seems probable 
that their disposition was uniserial and abbreviate in obtusely 
lobate fins and biserial in acutely lobate fins. In the remaining 
Teleostomi (Actinopterygii) the endoskeletal elements become 
1 Budgett, Trans. Zool. Soc. xvi. Part vii. 1902, p. 328. 
