1859.] EGERTON OLU KKD FISHES. 125 



are so similar to Osteolepis, that I was at first inclined to regard it 

 as a specimen of that genus in which one dorsal fin had not been 

 preserved. The position, however, of the other dorsal, opposite to the 

 anal, is a character, not of Osteolejpis, but of Diplopterus, from which 

 genus it differs in many respects, and especially in the form of the 

 tail. I am therefore inclined to admit the validity of the genus. 

 The figure in the ' Poissons Fossiles,' alluded to as probably belonging 

 to this genus, is undoubtedly that of a true Osteolepis. In conse- 

 quence of compression, the scales of the left flank are thrown up, 

 thus exaggerating the breadth of the fish. The dorsal ridge, how- 

 ever, is traceable ; and a large scale is visible which marks the posi- 

 tion of a first dorsal fin in advance of, and not opposite to, the first 

 anal fin. 



In the family of the Ccelacanthi, the genus Glyptolepis is first 

 noticed. In the generic character, it is described as having " one 

 (J<t ached ventral Jin." This must be a typographical error, as Prof. 

 M'Coy's anatomical knowledge is too great to allow him to advance 

 such a heterodox axiom as a one-legged vertebrate. 



Immediately in succession to Ghiptolepis, Prof. M'Coy places 

 DinERus, and he suggests, by a note of interrogation, that the two 

 genera may possibly be united. I entirely agree with him in the 

 propriety of classifying this genus with the Ccelacanthi rather than 

 with the Sav/rodipteridoB ; but it is very distinct generically from 

 Glyptolepis. Prof. Agassiz and Prof. M'Coy arc both in error in 

 ascribing two anal fins to THpterus*. This has arisen from the very 

 remote position of the ventral tins. The fringed or lobate cha- 

 racter of these organs is peculiar to the double fins, and is never 

 Been in the dorsal and anal fins ; it therefore affords a good criterion 

 in cases of doubt. This feature is very distinctly shown in M. Scharf's 

 figure 'A. pi. 15, Trans. Geol. Boc. 2 ser. vol. iii.. and proves that this 

 fin, which Prof. M'Coy alludes to as an anal fin, is truly a ventral 

 fin, its fellow being concealed beneath the body of the fish. The 

 true arrangement of tbe tins of Jjij/lirus is admirably well sbown 

 in the wood-cut of this genus ai page 287 "I' the lasl edition of 

 • Biluria,' where the small anterior dorsal tin is seen Immediately 

 above the Lobateventral tins. The determination of specific character 

 in this genua is most difficult. The scales are so loosely attached 

 that they slide over each other under the slightesl pressure, con- 

 cealing or exposing a greater or smaller area ^ the case may be : 

 and the tin-rays are ■"> delicate, especially in their distal extremities, 

 and consequently bo liable to abrasion or non-preservation, thai little 

 reliance can he placed on their relative Length. Prof. Agassiz, after 

 a careful examination of all the original specimens, came to the 

 conclusion thai they constituted hut one species. Prof. M'Coy, on the 

 contrary, rev ives the three species originally described in the memoir 

 of Sedgwick and Kfurchison. The result of my owl ition 



is. that Agassis was justified in uniting Diptenu brachypyyopterui 

 with I). macropygopterw, hut that Diptenu Valtncicnnesi oughl to 



For the best description ofDij Sketchbook of Popular Geo 



li _ii Miller, p 24tt. 



