4 OLD RED SANDSTONE EISHES. 



In the 'Quart. Journ. Geol. Soc' for 1860 Professor Huxley published a paper in 

 which he showed the true nature of Roemer's Palaoteuthis (see also fig. 10, p. 20), already 

 alluded to, and at the same time gave a restored outline of the shield of the Cephalaspis 

 {Pteraspis) rostratus of Agassiz. 



In 1863 I had the good fortune to obtain a specimen of Pteraspis, showing a few 

 rhomboid scales attached to the shield, and thus the piscine nature of the fossils was 

 definitely set at rest. (Plate V, fig. 3.) 



In ' Decade X' of the Geological Survey published in 1861, Professor Huxley consti- 

 tuted the family CEPHALASPiDiE to receive the genera Cephalaspis, Auchenaspis, Pteraspis, 

 and Menaspis. This family he placed among the Chondrostean Ganoids, where he 

 considered it should have a very distinct position. 



At the Meeting of the British Association at Bath^ 1864, I proposed to divide the 

 genus Pteraspis, as adopted by Professor Huxley, into three other genera, in accordance 

 with three degrees of complexity in the structure of the head-shield observable in the 

 known species : and in the following year, at Birmingham, I briefly reviewed the species 

 of Cephalaspis then known, and exhibited specimens of these Fishes, of great interest, 

 discovered by Mr. Powrie, in Forfarshire. Lastly, in the ' Geological Magazine ' for 

 April, 1867, I described the genus DidT/masjns, allied to Cephalaspis and Auchenaspis. 



The following list contains references to all, I believe, that has been written on the 

 Fishes of the Family Cephalasjndce, the titles of the papers being given in chronological 

 order : 



Agassiz. ' Recherches sur les Poissons fossiles,' vol. ii, p. 135, pis. la, \h, 1835. 



,, 'Monogr. Poiss. Vieux Gres Rouge,' p. 31, 1844. 



Kner [Cephalaspis Lloydii, C. Lewisii, and a new species). Haidinger's 'Naturw. Abhandlungeu,' 



vol. i, p. 109, 1847. 

 EiCHWALD {Thyestes verrucosus). 'Bullet. Societd Imp. Nat. Moscou,' p. 108, 1854. 

 EvTALD (Menaspis). Proceed. Acad. Berlin, p. 33, 1848. 

 Pander {Ceph. verrucosus and C. Schrenkii). 'Monographie der fossilen Fische des Silur-Systems,' 



p. 47, 1856. 

 Huxley and Salter {Pteraspis truncatus and Pt. Banksii). ' Quart. Journ. Geol. Society,' vol. xii, 



p. 100, 1856. 

 Egerton (Ceph. Murchisoni, C. Salweyi, and C. ornatus, and Auchenaspis). 'Quart. Journ. Geol. 



Soc.,' vol. xiii, p. 282, 1857. 

 Huxley (Structure, &c. of Cephalaspis and Pteraspis). 'Quart. Journ. Geol. Soc.,' vol. xiv, 

 p. 267, 1858. 

 „ (Observations on Pteraspis). ' Brit. Assoc. Report,' 28tb Meeting, Trans. Sect., pp. 82, 

 83, 1858. 

 Harley {Ceph. asterolepis) . ' Quart. Journ. Geol. Soc.,' vol. xv, p. 503, 18-59. 

 Salter {Pteraspis from the Ludlow Beds). ' Annals and Mag. Nat. Hist.,' 3rd ser., vol. iv, pp. 44 



—48, 1859. 

 Huxley {Palceoteuthis and Restoration oi Pteraspis). 'Quart. Journ. Geol. Soc.,' vol. xvii, p. 163, 

 1860. 

 „ (Zoological Position of Cephalaspidce) . 'Memoirs of Geol. Survey, Decade X,' p. 38, 1861. 



