98 Dr. R. H. Traquair—A New Species of Dipterus. 
Valenciennesii, in order that the honour which the proposers of that 
name wished to confer on the distinguished French ichthyologist 
might not thereby be lost. As he also constantly uses the name D. 
— “nlatycephalus,” it would appear that he considered these large 
crania also to constitute a distinct species. 
After a careful examination of a very large number of specimens, 
including Sedgwick and Murchison’s original types, in the Museum 
of the Geological Society, I have come to the same conclusion as 
Pander, namely, that the species, brachypygopterus, macropygopterus, 
and Valenciennesti are one. In the original type-specimens the 
apparent difference in the size of the anal fin in the first two reputed 
species is certainly due to the mode in which the specimens have 
been crushed, and as to Valenciennesii, I can only recognize in it a 
young example of the same common species. In the same way the 
adult condition of this species is to my mind represented by the 
large heads which have been called “ platycephalus.” 
If we follow, with absolute strictness, the rules of the British 
Association in adopting the first of the specific names given by 
Sedgwick and Murchison, then we shall be compelled to use the 
very inappropriate one of “ brachypygopterus,” as well as to deprive 
the name of Valenciennes of the homage which the discoverers of 
those fishes wished to offer toit. I hope, therefore, that the scientific 
world will grant an indulgence to Pander’s view, and allow the 
name Dipterus Valenciennesti to stand for the species in question. 
D. Valenciennesii is very characteristic of the Lower Old Red 
Sandstone of Banniskirk and Thurso, but it occurs also in the fish 
beds of the shores of the Moray Firth, as at Cromarty (Hugh Miller 
Collection) ; Lethen (Museum of Science and Art); Nairnside near 
Inverness (Wallace); Tynet (Collection of Rev. Mr. Kyle at 
Presholm, Banffshire). 
Another and very distinct species occurs, however, at John 
O’Groats, where it was discovered by the late Mr. C. W. Peach in 
the same beds which yielded Tristichopterus alatus, Eg., and Micro- | 
brachius Dickit (Peach). It is mentioned in Dr. A. Geikie’s list of 
Old Red Fishes,! and has been very briefly characterized by myself 
in a recent number of the Grotocican Macazinn, where I proposed 
for it the name of Dipterus macropterus.? In the present communica- 
tion I propose to give a somewhat more detailed description of this 
interesting form, accompanied by the figures on Plate II. 
Ordinarily at least this species does not seem to have attained 
any great dimensions, as the specimens in the Hdinburgh Museum 
average about six inches in length. In general form (Fig. 1) it 
resembles D. Valenciennes, and the osteology of the head appears 
to be similar, though I have not found the ctenodont plates preserved 
in any instance. In Fig. 2 the outlines of the plates of the posterior 
part of the cranial buckler are given, from which it appears that 
they are rather shorter and broader than the corresponding plates in 
D. Valenciennesii, and there is an absence of the small plate which in 
1 Trans. Royal Soc. Edin. vol. xxviii. p. 452.. 
2 Grou. Maa. for November, 1888. 
