PALEONTOLOGY 



In sinking a well in the yard of the Crown Inn at Allenton near 

 Derby, a number of mammalian bones were discovered. These were 

 carefully dug out, and after being examined and described by Mr. H. H. 

 Arnold-Bemrose, 1 were deposited in the Derby Museum. The majority 

 are referable to the Pleistocene hippopotamus, but one belongs to an 

 elephant and another to a rhinoceros. 



The following species are recorded from the Carboniferous forma- 

 tions of the county in the British Museum Catalogue of Fossil Fishes. 

 Commencing with those of the Mountain Limestone, we have first of 

 all three sharks belonging to an extremely primitive and totally extinct 

 group known as the Ichthyotomi. Two of these, Cladodus mirabilis and 

 C. striatus, belong to a genus containing several species, both being 

 typically from the Mountain Limestone of Armagh. The third, Dicre- 

 nodus dentatus, which was likewise first described from Armagh, is the 

 sole representative of its genus. Among the rays and true sharks 

 (Selachii), a representative of a widely- spread Carboniferous genus, 

 Janassa imbricata, is peculiar to the upper division of the Mountain 

 Limestone of the county, the two type teeth (apparently the only known 

 remains of the species) having been obtained from Ticknall near Mel- 

 bourne, South Derbyshire. 2 A more widely-spread species, J. clavata, 

 also occurs at the same place. The mouths of the primitive rays of this 

 genus were furnished with- crushing teeth of a very peculiar and un- 

 mistakable type. From the same locality have been obtained teeth of an 

 allied kind of ray, Petalorbyncbus psittacinus, which is common to the 

 Carboniferous rocks of Armagh. The typical genus of the same family 

 of rays (Petalodontidce] is represented by two species, Petalodus acuminates 

 and P. hastingsite, from the Mountain Limestone of Ticknall, neither of 

 which is, however, peculiar to the county. To the allied family Pristo- 

 dontidce belongs Pristodus benniei, a species first described from Scotland, 

 but also known by teeth from Ticknall. 



Another Palasozoic family of ray-like selachians, the Psammodontidce 

 (at present only known by their dentition), are represented in the Carbon- 

 iferous or Mountain Limestone of the county by Copodus spatulatus and 

 Psammodus rugosus, both being widely spread forms belonging to genera 

 with several species. The crushing teeth of Psammodus are in the form 

 of large quadrangular flat plates, with a surface suggestive of sandpaper 

 hence the name. 



Other fishes from the Mountain Limestone of the county, known as 

 Pleuroplax attbeyi, PI. woodi, Psepbodus magnus, Xystrodus striatus, Pcecilodus 

 ionesi, Deltoptychius acutus, and D. gibberulus, all of which were originally 

 described from other localities, indicate the occurrence of an imperfectly 

 known family of Palaeozoic sharks (Cochliodontidee) with crushing teeth, 

 which appear to have been distantly related to the modern Port Jackson 



1 Quart. Journ. Geol. Soc. Hi. 497. 



2 A list of twenty species from this locality is given by E. Wilson (Midland 'Naturalist, iii. 172) ; 

 many of the names are however synonyms, while others were applied to specifically indeterminable 

 specimens, and others, again, have been amended. It would therefore be useless to quote the list 

 seriatim. 



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