On Species 0/ Ehadiiiichtliys /ro7/i the Coal Measures. 241 



of the under surface and the articular spine well marked. 

 The exposed surface is ornamented with exceedingly well- 

 marked elevated ridges, passing across the scale from before 

 backwards with a slight downward obliquity, and ending in 

 denticulations of the posterior margin. These ridges tend 

 constantly to become broken up into isolated tubercles, or, 

 conversely, the ornament may be described as consisting of 

 raised tubercles, tending constantly to a linear arrangement, 

 and to coalescence into ridges. 



Remarks. — Rhadinichthys Wardi may be at once distin- 

 guished from all the other species of the genus by its peculiar 

 ridged and tuberculated scale sculpture, a form of scale 

 ornament which is exceedingly rare in the entire family of 

 PalceoniscidcB. In the general form and proportions of the body 

 it resembles R. ornatissimus, though it does not seem to have 

 attained so large a size as that Lower Carboniferous species. 



Geological Position and Localities. — Not uncommon in the 

 coal measures of North Staffordshire, especially in the " Ash 

 Coal" shale at Fenton and Longton (collection of Mr J. 

 "Ward, F.G.S.) ; in the coal measures of the neighbourhood of 

 Manchester (collection of Mr J. Plant, F.G.S.) ; in the shales 

 of the Lanarkshire coal-field (collection of Geological Survey 

 of Scotland). 



2. Rhadinichthys monensis, Egerton sp. 

 Palceoniscus monensis, Egerton, Qu. Journ. Geol. Soc. Lond., 1850. 



This species has hitherto been known only from detached 

 scales which were figured by Sir Philip de M. Grey -Egerton 

 in 1850, as Palceoniscus monensis. The general resemblance 

 which these scales bore to those of Rhadinichthys carinatus, 

 Ag. sp., and R. hrevis, Traq., though their sculpture is much 

 more marked (the scales of R. carinatus being in fact nearly 

 smooth), led me long ago to suspect that they were allied 

 forms. It was, however, only very lately, while looking over 

 some fish remains collected by the Geological Survey of Scot- 

 land, that I obtained what seems to me to be clear evidence 

 that the place of Sir Philip Grey-Egerton's fish is in the 

 genus Rhadinichthys. These specimens, as usual, consist of 

 disjointed scales ; one of them, however, shows a con.siderable 



