ON PTERASPIS DUNENSIS 419 
fossil shell indicates its affinity rather with Sepza than with Lo/zgo, as 
I had previously supposed.” 
The specimen from Wassenach thus described has now passed into 
the collection of the British Museum ; and my friend Mr. Woodward 
(who had already divined the precise nature of the so-called Palgo- 
teuthis in a note to p. 417 of his ‘Manual of the Mollusca’) having 
called my attention to the specimen, without giving me any informa- 
A B 
e 
DIAGRAM OF A RESTORED PTERASPIS. 
a. Snout or rostrum, united with 4, the shield-like disk. c¢. The cornua of the latter ; d, its 
median backward prolongation; e, the median posterior spine into which the last is 
produced. f£ Orbits or nasal apertures. 
tion as to its previous history, I at once affirmed it to be a Pteraspis, 
—being led to this determination by the eminently characteristic 
striation of the outer surface, combined with the no less peculiar 
polygonal cells of the middle layer There is nothing like either 
1 Ts have carefully described these structures in my memoir ‘On Cephalaspzs and 
Pteraspis,” Quarterly Journal of the Geological Society, 1858, vol. xiv. 
ty 
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