148 GANOID FISHES OK TIIK C VllUONlFKllOUS FOIIMVLUO.V. 



specimens wliich I have examined. The operciilum (Text-fig. 7) is broad, the sub- 

 opercuhim trapezoidal, the anterior margin being only half as long as the posterior. Mr. 

 Atthey described the operculum as " suiooth," but the fact is that only the internal 

 surface of it as well as of the suboperculum is seen. 



The scales are hard to describe, being much broken, and for the most part only seen 

 from their internal surfaces. It is to be noted, first, that there are along the flank two 

 rows of scales which are much higher than the others. Mr. Atthey described their 

 external surfaces as " smooth," but I am of opinion that, as in the case of the opercular 

 plates, oidy their itnicr surfaces are exhibited. Traces of the outer surfaces are, however, 

 occasionally seen, and these display an undoubted rugose ornament. The posterior 

 border of these scales is finely denticulated. The other body-scales are much smaller, 

 except a long ridge-scale, which, in one specimen, is seen in front of the dorsal fin. 



The pectoral fin (see fig. 1) is small, and contains about ten rays, which are 

 unarticulated for the greater part of their length; very oblique fulcra may also be 

 distinguished along its anterior margin. 



The vcntrals (see fig. 2) are situated midway between the pectoral and the anal ; 



Fig. 7. — Skutch to slio.v thn form of tlie oiieiTular bones in Rh'uUiuchth'^s Sancocki (Atthey); o^., operculuui; 

 «.o/)., suboperculuni; ;««., mamtible; />., pectoral fin. 



they are also small, but their rays, which are smooth with distant articulations, cannot 

 be counted. 



In no specimen are the dorsal and anal completely preserved, but their remains are 

 seen in the specimen represented in fig. 2. There the dorsal is seen to be placed nearly 

 opposite the anal, and in the case of both fins the rays are rather disturbed and not all 

 of them seen ; their surfaces are smooth, and their transverse articulations distant. 



The caudal fin is seen badly in two of the specimens; it is heterocercal, inequilobate, 

 the prolongation of the body-axis in the upper lobe being very weak. 



Observations. — An undoubted I{hadi7iichthi/s, the present species is distinguished 

 from all the other known members of the genus by the longitudinal bands of high-shaped 

 scales along the flank. 



Geolof/ical Position and Localities. — From the roof-shale of the Low Main Coal Seam 

 at Newsiiam, near Newcastle-on-Tyne. The type specimens, collected and described by 

 the late Mr. Thomas Atthey, are in the Museum of the Natural History Society, New- 

 castle, and I have to acknowledge my indebtedness to the Council of the Societv, as well 

 as to Mr. Leonard Gill, Curator of the Museum, for the loan of these specimens for the 

 purposes of the present work. 



