Dr. R. H. Traquair—Old Red Sandstone Fishes. 511 
p. 72).—Very small, head and carapace only attaining a length of 
1+ inch. Arrangement of head-plates not decipherable, carapace 
depressed, anterior median dorsal plate broad, overlapped by the 
posterior dorso-lateral, and also by the anterior dorso-lateral, except 
towards its anterior angles, where the condition is suddenly reversed ; 
surface minutely tuberculated ; arms very short; no trace of tail or 
of caudal scales. In the Museum of Science and Art, Edinburgh, 
collected by the late C. W. Peach, from the Lower Old Red Sand- 
stone of John-o-Groats, Caithness. 
Owing to the apparently depressed shape and the absence of 
caudal scales, I should have included this strange little species in 
Bothriolepis, were it not for the shortness of the arms, and the 
peculiar articulation of the anterior median dorsal plate. I there- 
fore venture to propose a new genus for its reception. 
Family Coccosre1pz. 
Coccosteus, Agassiz.—With regard to Coccosteus, I believe that 
C. oblongus, Ag., cuspidatus, Ag., microspondylus and trigonaspis, 
McCoy, and Milleri, Eger., are all synonyms of C. decipiens, Ag. I 
rather think that C. pusillus, McCoy, is also a young specimen of the 
same species, and if so, then the name C. minor, Hugh Miller, should 
be applied to the small Thurso specimens (see Cruise of the Betsy, 
chap. x.) collected by Robert Dick, which most certainly are ex- 
tremely distinct from the ordinary Moray Frith and Orkney examples 
of the genus. I cannot agree with v. Koenen in referring the 
specimen figured by Agassiz in his ‘‘ Old Red,” tab. x. fig. 1, as one of 
C. decipiens, and afterwards named by Egerton C. Milleri, to his new 
“subgenus” Brachydeirus (see “ Beitrag zur Kenntniss der Placoder- 
men des norddeutschen Oberdevons,” Abh. Kén. Gesellsch. der Wis- 
sensch. 1883), and I may also state that among the hundreds of 
examples of Coccosteus from Scotch deposits which I have examined, 
I have never found the slightest trace of the pectoral spine, repre- 
sented in his restoration of Brachydeirus (ib. pl. iv. fig. 1). 
Homosteus, Asmuss.—As there can be no doubt that Agassiz was 
in error in attributing to Hichwald’s Asterolepis, Asmuss’s “‘ Riesen- 
knochen” from Dorpat, afterwards referred by the last-named author 
to two genera, Homosteus and Heterosteus, the name Homosteus, 
Asmuss, must certainly be applied to the “Asterolepis of Stromness,” 
whose remains were first figured by Hugh Miller in his “ Footprints 
of the Creator.” As there is no evidence that this gigantic Coccostean 
belongs to any of these species named by Asmuss, I propose to name 
it Homosteus Milleri. 
Suborder ACANTHODEI. 
Family AcanrHoDIDZ. 
Mesacanthus, n. gen. Traq. (=Acanthodes, Agassiz pars).—The 
small Acanthodes-like fishes of the Scottish Lower.Old Red Sand- 
stone differ from Acanthodes of the Carboniferous and Permian 
rocks by the presence of a pair of small intermediate spines in the 
belly between the pectoral and ventral spines. Here may be 
