STRUCTURE OF CERTAIN PALEOZOIC DIPNOI. 
205 
DlPTERCS VALENCIENNESI, Sedg. & Murch. 
Dipterus valenciennesi is a small fish, found very abundantly in the western 
■end of the mainland o£ Orkney and at Banniskirk, Achanarras, and other 
localities in Caithness, and, except at Edderton Burn, only very rarely in the 
nodules o£ the Moray Firth. 
It was distinguished from the more recent D. i^latyceplialus by Pander on 
account of its smaller size, lack of shiny surface on the cranial bones and 
scales, and lack of well-ossified anterior ends of the skull and mandible. 
Dr. Traquair, presumably because large specimens which in these characters 
agree with D. plati/cepJialus do occur at Achanarras, G-amrie, and Cromarty 
and in association with a small fish which he regarded as D. valenciennesi at 
Fig. 32. 
L.q.3. 
L.Q.4.5.6. 
Dipterus vaknciennesi, Sedg. & Murch. Right lateral aspect of a crushed head. X 2. 
From a specimen in D. M. S. Watson's collection. 
Clav., clavicle ; Olei., cleithrum ; L.G. 3-6, lateral gulars, nos. 3-6 ; Md., mandible ; 
Mx., maxilla; Op., operculum; P.G., principal gular; P.Tem., post-temporal; 
S.Cl., supra-cleithrum ; S.Op., sub-operculum. 
the Gloup in Orkney, combined the two species. "Watson and Day pointed 
out a distinguishing feature in the fusion in D . platyceplialus of the tabulars 
and interparietal with the bones immediately in front of them, which remain 
separate in D. valenciennesi. 
Amongst the hundreds of specimens of D. valenciennesi which we have 
seen, only three show the bones of the cranial roof clearly ; few show anything 
of the gular apparatus, aiTd only one shows the lateral surface of the head 
clearly. 
