A HISTORY OF DERBYSHIRE 



shark and its allies (Cestraciontidce) . Certain teeth of this type from 

 Ticknall have been described as Venustodus serratus. 



Two species, Acrolepis hopkinsi and A. ivi/soni, of a Carboniferous 

 genus of ganoid fishes have been described upon the evidence of scales 

 from the county. Of the former species, which is from the Mountain 

 Limestone, and is also known from other localities, the type specimens 

 are in the Cambridge Museum. Of the latter, which is peculiar to the 

 county, the types (now in the British Museum) were obtained from the 

 Yoredale Rocks of Turnditch near Helper. 



A splenial bone from the Mountain Limestone of the county 

 preserved in the Woodwardian Museum, Cambridge, was described by 

 McCoy in 1848 as Cbeirodus pes-rance. It indicates a member of the 

 ganoid family Platysomatidce, but is insufficient for accurate diagnosis. 



The fishes of the Derbyshire Coal Measures belong, with one excep- 

 tion, to the ganoid or hard-scaled group. The exception in question is 

 Sphenacanthus hybodoides, a widely-spread species of a numerously repre- 

 sented Carboniferous genus. Of the Coal-Measure ganoids the first is 

 Rhizodopsis sauroides, remains of which have been obtained from the 

 Dalemoor Rake Ironstone of Stanton-by-Dale. This widely distributed 

 species is a member of a large genus belonging to a family (Rhizontidce) 

 characterized by the complicated internal structure of the teeth, which 

 in this respect correspond to those of the primitive salamanders, or 

 labyrinthodonts. Another family (Osteolepididtz) of fringe-finned ganoids 

 is represented by two widely-ranging species, Megalichthys hibberti and 

 M. pygmceus, of a well-known genus restricted 'to the Coal Measures 

 and Calciferous Sandstone. The Ironstone of Stanton has also yielded 

 remains of Ccelacanthus e/egans, a member of the type genus of an allied 

 family of the same great group of ganoids. Peculiar to the Dalemoor 

 Rake Ironstone of Stanton-by-Dale is the fish known as Platysomus tenui- 

 sfriatus, a representative of the typical genus of a family belonging to a 

 totally different group of ganoids, in which the fins have a rayed and not 

 a fringed structure. The type of this species is a whole fish in the 

 Museum of Practical Geology, Jermyn Street. 



Since the above was written Professor W. B. Dawkins exhibited 

 before the Geological Society of London (Jan. 7, 1903) a number of 

 molar teeth of Mastodon arvernensis from a cave at Doveholes, Buxton. 

 This mastodon is a Pliocene species, occurring in the Norwich and 

 Red Crags of England, and in the Upper and Lower Pliocene of the 

 continent. Its remains have never previously been found in a cave, 

 neither, I believe, is any other instance known of a cavern containing 

 fossils of Pliocene age. 



