1 8 WATSON & DAY, Notes on some Palceozoic Fishes. 



They seem to show some differences in squamation, two 

 large individuals having nearly rhomboidal scales with a 

 definite chevron pattern of sharply marked ridges, whilst 

 the smaller individuals have more rounded and much less 

 definitelv ornamented scales. 



Gyroptych ins m icrolepidotits. ( A g. ). 



Three well preserved specimens of Gyroptyckius, one 

 from Tynet Burn, the others from the Enstabile Quarry 

 in the parish of Sandwick in Orkney, allow us to add to 

 the existing knowledge of this fish. The structure of the 

 head seems to be, as it has already been represented by 

 Traquair, nearly identical with that of Osteolepis, there 

 being a single large cheek plate corresponding with 

 the squamosal, pre-operculum, and quadrato-jugal of 

 Rhizodopsis. The pectoral fin differs from that shown in 

 Dr. Traquair's figure in its considerably greater size and 

 in the large somewhat bluntly pointed scaly lobe which 

 bears a great resemblance to that of Glyptopomus and 

 differs markedly from the broad bluntly terminated lobe 

 of the pectoral in Rhizodopsis. The specimen L. 8432 

 from Tynet shows very clearly the presence of a pair 

 of elongated elements, thick semi-cylindrical scales, 

 associated with the pelvic fins. These agree precisely 

 with the similar bones we have described in Rhizodopsis. 

 The extreme attenuation of the scaly caudal lobe is very 

 well shown in this fish, the whole of whose caudal 

 extremity considerably resembles that of Rhizodopsis. 

 One of the Orkney specimens, L. 8431, shows the 

 ornamentation of the scales very beautifully. They are 

 quite rhomboidal scarcely more rounded than in Osteolepis 

 and ornamented with V shaped ridges directed backwards 

 on the exposed area of the scale. 



