Geology and Geography. 429 



describ3(l by Messrs Sedgwick and Murchison ; and also some fishes 

 from Gamrie, of which Mr Murchison possesses a very perfect col- 

 lection. 



Of the fossil fishes not from Scotland, which I have seen on the 

 present occasion, I shall take another opportunity to speak. 



As to the determination of the Scottish fishes, I must remark, ge- 

 nerally, that they all belong to two orders of the Class, viz. some 

 to the order of Placoidian fishes, Agass. (Cartilagineux, Cuv.) ; but 

 the larger number to the division Ganoidian fishes, Agass., and two 

 to the section Heteocerei, in which the upper lobe in the caudal fin 

 is longer than the lower. 



' In the old red sandstone, there are two species from Glammis, 

 Forfarshire, viz. one species of the genus Cephalaspis (Ganoidian), 

 which has hitherto been found in this formation only. The most 

 remarkable characters of this genus are the shield-like covering of 

 the head, and which is prolonged backwards in the form of two 

 horns as in the Trilobites, and the manner in which the eyes are 

 placed near each other on the head. The other species belongs 

 probably to the genus Hybodus (Placoidian), but of this I have seen 

 only an Ichthyodorulite. 



The fishes from Caithness and Orkney approach one another most 

 nearly ; though amongst the latter there are several new genera, 

 and in all eight species. Those from Caithness seem to belong to 

 two species only. Amongst the Orkney fishes there are two very 

 remarkable genera resembling the Acanthodes of the coal formation, 

 also having very small scales ; but the new Cheiracanthus is fur- 

 nished with a spine in the pectoral fin only, and the other, the 

 Chirolepis, instead of having the spine is provided with a row of 

 small scales. I have been convinced by the examination of many 

 specimens, that the genus Dipterus has two dorsal fins. In Orkney 

 there are also species which have two dorsal fins and two anal 

 fins, which sometimes are opposite one another, and sometimes al- 

 ternate ; and these are types of two genera, the Diploptertts and the 

 Pleiopterns. 



The fishes from Burdiehouse <ire also very numerous ; in their 

 characters they agree with those of the coal formation, but are 

 more removed from those of Saarbriick than are the remains found 

 at Newhaven. The most remarkable amongst them is an animal 

 which, from the structure of its teeth, might be considered as a 

 reptile, and which must have been of very considerable dimen- 

 «ions ; but which, from its skeleton and its scales, is decidedly a 



VOL. XVII. NO. XXXiV. — OCTOBER 1834. F f 



