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XX. — On a New Species of Cephalaspis, discovered by the Geological Survey of 

 Scotland, in the Old Red Sandstone of Oban. By Eamsay H. Traquair, M.D., 

 LL.D., F.R.S., Keeper of the Natural History Collections in the Museum of Science 

 and Art, Edinburgh. (With a Plate.) 



(Read 4th July 1898.) 



In the autumn of last year Sir Archibald Geikie, F.R.S., Director-General of the 

 Geological Survey of the United Kingdom, kindly placed in my hands for determination 

 a number of specimens of Cephalaspis, collected by his officers in theXower Old Red 

 Sandstone of the neighbourhood of Oban. On examining them, I found 'that thev all 

 belonged to one species, which was, however, new to science. 



Accordingly I drew up a brief diagnosis of this "new form, which was included "by 

 Sir Archibald in his Summary of Progress of the Geological Survey for 1897, and it 

 is now my privilege, with his sanction, to offer to this Society a more detailed descrip- 

 tion of the species, accompanied with figures. 



Class, PISCES. 



Sub-class, OSTRACODERMI. 



Order, OSTEOSTEACI. 



Family, CEPHALASPID^. 



Genus, CEPHALASPIS, Agassiz, 1835. 



Cephalaspis Lornensis, Traquair. 

 Cephalaspis Lomensis, Traq. In the Director-General's Summ. Proyr. Geol. Survey for 1897 (1898), p. 83. 



Diagnosis. — Shield bluntly rounded in front ; cornua short, considerably shorter 

 than the occipital projection ; eyes placed considerably in front of the middle point 

 between the anterior margin and the posterior extremity of the shield. 



The distinctive marks of this species are the short cornua, together with the anterior 

 position of the orbits. This is illustrated by the accompanying restored outlines of the 

 cephalic shield in C. Lornensis (fig. 2) and in the common C. Lyelli of the Lower Old 

 Red of Forfarshire and Herefordshire (fig. 1 ). 



As regards the cornua, the known species which most closely approaches C. Lor- 

 nensis is C. Murchisoni, Egerton (fig. 3), from the Passage Beds (Downtonian) of 



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