9(3 



THE GEOLOGIST. 



to strengthen that conviction." (I had just written him to that effect.) 

 Mr. Walker has, undoubtedly, the merit of first making this discovery 

 public ; this he did in an admirbale paper, describing most accurately this 

 species, H. Flemingi, and stating his conviction that it belonged to the 

 genus Glyptolepis. This paper was read on, I think, the 22nd of Novem- 

 ber last, before a meeting of the Literary and Philosophical Society of St. 

 Andrew's, and has since been published in the ' Annals and Magazine of 

 Natural History.' 



Not only must the Holoptychius Flemingi hereafter be looked on as 

 belonging to the genus Glyptolepis, but it seems to me exceedingly pro- 

 bable, that Holoptychius may ere long be altogether merged into that 

 genus. The only species of Holoptychius on which I have never yet been 

 able to detect scales, showing the crescent of points on the anterior half so 

 characteristic of those of Glyptolepis, is H. Andersoni, and this I am at 

 present inclined to think not a good species at all. Of Holoptychius 

 giganteus, the only good specimen I have yet examined is the superb one 

 in the collection of Lady Kinnaird ; of this it is the ventral surface which 

 is exposed, and on the anterior portion the scales show very distinctly the 

 characteristic markings of the Holoptychius giganteus of Agassiz ; along 

 the flanks on both sides they as clearly assume the Glyptolepis character, 

 in many instances showing the crescent of points so distinctly as to be 

 readily observed by the unaided eye, while towards the tail the scales 

 assume the exact appearance of those on Holoptychius Andersoni ; indeed, 

 so exactly does this fish resemble H. Andersoni in form, in the comparative 

 size and disposition of the scales, in the position, structure, and form of 

 the fins, so far as preserved, in the comparative size and form of the head 

 and jugular plates, indeed in everything except size, that I am much 

 inclined to think H. Andersoni the young of II. giganteus, increased age 

 developing the different sculpturing on the scales. Mr. Walker refers in 

 his paper to a very imperfect specimen of this fish in the St. Andrew's 

 Museum, the scales along the flanks also showing the crescent of points 

 on the anterior half, the others resembling those of H. giganteus. Mr. 

 Walker also pointed out to me what I fully concur with him in thinking a 

 species, nearly allied to, but distinct from Flemingi, with which it 

 seems hitherto to have been confounded, and in this every scale sufficiently 

 preserved appears to have the crescent of points as in Glyptolepis. In a 

 specimen now in my possession, which was obtained by the late Mr. 

 P. Dull' of Elgin, from the Bishop Mill (Elgin) sandstones, and which has 

 been named, I think correctly, nobilissimus ; I have also been able to 

 detect one scale having the crescent of points well preserved, and I am 

 informed by Professor Huxley, that the typical specimens of Holopt. 

 Sedgwickii, in the Cambridge Museum, present unmistakable Glyptolepis 

 scales. 



Mr. Mitchell mentions a Paper communicated by me to the Geological 

 Society of London, and published in their Journal for November last, in 

 which I first drew attention to the occurrence of Glyptolepis scales in the 

 Dura Den Sandstones, and in which I notice a fish as a new species of 

 Glyptolepis. This fish, however, I now believe to belong to some other, 

 probably new genus, the caudal and other fins, as w r ell as the general form 

 too little resembling Glyptolepis, while of the scales it is only the internal 

 structure which is shown, and although on one or two the external sculp- 

 turing- is imperfectly preserved, yet the body where these are situated 

 being a good deal twisted, they may have belonged to some of the many 

 other fishes scattered over the flag on which this is preserved. 



Thus at present stands the case Holoptychius versus Glyptolepis ; it is, 



