Devonian Hishes of Campbelltown and Scaumenac Bay. 117 
backwards separating the anterior ventro-lateral below 
from the antero-lateral above. This process, short in C. 
decipiens, is more largely developed in C. minor, H. Miller, 
in which species I have stated that it has a “very spine- 
like appearance,” though, owing to the proportionally greater 
extent of the margins of the antero-lateral and anterior 
ventro-lateral plates with which it articulates, it forms no 
more of an independent projection than in the former. But 
as in Phlyctenaspis this spine seems divided by a very 
distinct suture from the interlateral plate, I have carefully 
examined the suite of specimens, both of Coccosteus decipiens 
and C. minor, in the Edinburgh Museum, with the result that 
I have convinced myself that the process in question is here 
also a distinct element, to which the name of “ lateral spine ” 
may appropriately be given. In both genera it is immovably 
fixed; in one example of Phlyctenaspis it seems indeed 
anchylosed to the interlateral plate. 
Consideration of this element of the cuirass of the 
Coccosteidee calls up, of course, the question of Acanthaspis, 
Newberry. Mr Smith Woodward? remarks that the spines 
of Phlyctenaspis “are indeed precisely similar in external 
form and appearance to those of Acanthaspis; and so far as 
can be judged from known specimens they only differ from 
the last-mentioned spines in the circumstance that the 
supporting plate is destitute of the extended oblique pedicle 
observed both’ in the type specimens from the Corniferous 
Limestone of Ohio, and in the shield assigned to the same 
genus from Spitzbergen. It thus remains to discover more 
associated examples of the plates and spines from Ohio, to 
determine whether they actually pertain to Ostracoderms, as 
suspected, or whether they represent part of the armour char- 
acteristic of Arthrodira; for the fixed spinous appendage is 
now proved to occur in both of these widely-separated groups.” 
It will be remembered that Mr Woodward, in a previous 
paper,® was inclined to consider Acanthaspis as being “ most 
1 R. H. Traquair, Geol. Mag., dec. iii., vol. vi., pl. i., fig. 3. 
2 Op. ctt., p. 481. 
’ Devonian Fish-Fauna of Spitzbergen—Ann, and Mag. Nat. Hist. (6), 
vol. viii., pp. 1-15, 
