Ch. XXVI.] 



OLD RED SAXDSTOXE. 



533 



several species now inhabiting the Xile and other African rivers. The 

 reader will at once recognize in Osteolepis (fig. 599) one of the coin 



Ksr. 599. 



Eestoration of Osteolepis. Pander. 

 Old Red Sandstone, or Devonian. 



a. One of the fringed pectoral fins. 



b. One of the ventral fins. 



e. Anal fin. 

 d, e. Dorsal fins. 



mon fishes of the Old Red Sandstone, many points of analogy with 

 Pohjpterus. They not only agree in the structure of the fin, as first 

 pointed out by Huxley, but also in the position of the pectoral, ventral, 

 and anal fins, and in having an elongated body and rhomboidal scales. 

 On the other nand, the tail is more symmetrical in the recent fish, 

 which has also an apparatus of dorsal finlets of a very abnormal char- 

 acter, both as to number and structure. As to the dorsals of Osteolepis, 

 they are regular in structure and position, having nothing remarkable 

 about them, except that there are two of them, which is comparatively 

 nnusual in living fish. 



Among: the " fringe-finned " Ganoids we find some with rhomboidal 

 scales, such as Osteolepis, above figured, and Diplopterus, Glyptolcemus, 

 and Glyptopomus ; others with cycloidal scales, as Holoptychius (see 

 fig. 588, p. 525), Dipterus, &c. The new genus Glyptolcemus, founded 

 by Huxley on specimens from the Devonian yellow sandstone of Dura 

 Den in Fife, is remarkable for having not only a fringe of rays entirely 

 surrounding a central lobe in the pectoral and ventral fins, but in hav- 

 ing the same structure repeated in the anal and both the dorsal fins. 

 In the genera Dipterus and Diplopterus, as Hugh Miller pointed out, 

 and in several other of the fringe-finned genera, as in Gyroptycliius and 

 Glytolepis, the two dorsals are placed far backwards, or directly over 

 the ventral and anal fins. 



The Asterolepis was a ganoid fish of gigantic dimensions. A. As- 

 musii, Eichwald, a species characteristic of the Old Red Sandstone 

 of Russia, as wel] as that of Scotland, attained the length of between 

 20 and 30 feet. It was clothed with strong bony armor, embossed with 

 star-like tubercles, but it had only a cartilaginous skeleton. The 

 mouth was furnished with two rows of teeth, the outer ones small and 

 fish-like, the inner larger, but with a reptilian character. The Astero- 

 lepis occurs also in the Devonian rocks of North America. 



If we except the Placoids already alluded to, and a few other 

 families of doubtful affinities, all the Old Red Sandstone fishes are 

 Ganoids, an order so named by Agassiz from the shining outer surface 



