SUPPOSED ANALOGIES OF POLYPTERUS. 211 



the reader : respecting the third, he will remember 

 that the primary character of the Cartilagines is not the 

 construction of their- skeleton, which applies only to 

 them as fishes, but the great breadth of their head, 

 which extends to all the classes of the vertebrated circle: 

 hence, even if the skeleton of the Lophidcs was not 

 semi-cartilaginous, yet the excessive size and width of 

 their muzzle assimilates them at once to the rays and 

 torpedos, which are the cartilaginous types. The ver- 

 tical outlines, in short, of the torpedo and the fishing- 

 frog, are almost so alike, that, if the details were not 

 filled up, one could hardly be distinguished from the 

 other. We have already stated the characters by which 

 Polypterus may be placed among the cheloniform fishes ; 

 and the analogy of the Syngnathidce to the apodal order 

 has also been touched upon. 



(184.) Our chief attention, however, must be di- 

 rected to Polypterus ; and, with the hopes of arriving 

 at more definite ideas regarding its true affinities, we 

 shall compare the presumed contents of the order Plec- 

 tognathes with those of the cartilaginous order, thus : — 



Analogies of the Plectognathes and the Cartilagines. 



Family of Analogies Families of 



Plectognathes. ^ ' Cartilagines. 



D 7- ^-j f The types generally furnished with spined f o 



Bahstzd^. J rays on their dor'sals. j Squalid^. 



Chironectidce. The fins always fleshy, and with soft rays. Raidje. 

 Lophidce. Head or muzzle excessively broad. Polyodonida. 



rBanchial aperture very open ; bodyT 

 Polypte7-idis[?).< mailed; mouth cirrated ; gill mem- >-STURiONiDiE. 



C brane one-rayed, or none. j 



r, w J C Tail long, attenuated : caudal fin obsolete, ? r^ 



SyngnathidcB. ^ ^^ n^ne ; mouth very small. j CniMiEEiDiE. 



Passing over the three first, we must confess that 

 our belief in the alliance of the Polypterus with the 

 Plectognathes is considerably strengthened, when we 

 now bring it into comparison with the sturgeons (Sturi- 

 onidcE), — a test vi'e had not applied to it when writing 

 the former paragraphs, because we wish this arrange- 

 ment to repose, not upon the analogies, but on the 

 affinities, of the groups. These two types are the only 



p 2 



