PALAEONTOLOGY 



majority of which are characterized by the sculptured bones of the skull 

 and the curiously complicated internal structure of their teeth. A lower 

 jaw of one of these creatures from Sidmouth has been made the type of 

 a species by Professor H. G. Seeley' under the name of Labyrinthodon 

 lavisi, while various unnamed remains of the same group obtained from 

 Sidmouth and Budleigh Salterton have been described by Mr. A. T. 

 Metcalfe." 



From the Rhastic formation of Axminster and Axmouth remains of 

 a small number of species of fishes have been recorded, none of which 

 however were named on the evidence of Devonshire specimens. They 

 include two species of an extinct genus allied to the existing Port Jack- 

 son shark, namely Hybodus minor from Axminster and H. cloacinus from 

 Axmouth. A fine specimen from the former locality belonging to the 

 type commonly known as Nemacanthus monilifer is not improbably refer- 

 able to Hybodus minor^ A tooth of a ganoid or enamel-scaled fish known 

 as Saurodon tomicus, belonging to the same family as the more common 

 Lepidotus, has also been obtained from the Rhstic bone bed at Axmin- 

 ster. Another family of ganoids is represented in the last mentioned 

 deposit by scales referable to a fish originally described from the Trias 

 of Germany under the name of Gyrolepis albertii. 



The Culm Measures of the county (like the Devonian formation) 

 seem to be singularly poor in fish remains, although those of two species 

 have been recorded from Instow. The first of these, Ccelacanthus elegans, 

 is typically an American species belonging to the group of fringe-finned 

 ganoids, of which the sole survivors at the present day are the bishir and 

 an allied type, both from Africa. The second, Elonichthys aitkeni, is a 

 species of a genus belonging to the same family {Palaoniscida) as the 

 above-mentioned Gyrolepis, and named on the evidence of Devonshire 

 specimens obtained by Mr. J. Aitken, 



In marked contrast to their comparative abundance in the fresh- 

 water Old Red Sandstone of Herefordshire is the scarcity in the approxi- 

 mately equivalent marine Devonian strata of Devonshire of remains of 

 those extremely primitive Palsozoic fishes respectively classed as Ostra- 

 codermi and Arthrodira. From the Lower Devonian of Mudstone Bay 

 there has however been obtained part of the head-shield of a pteraspid 

 {Ostracodermt) , although it is insufficient to allow of generic identifica- 

 tion. This and similar remains from the Devonian of Polperro in 

 Cornwall were originally described as fossil sponges, under the name of 

 Steganodictyum cornubicum!' The evidence for the presence of Arthrodira 

 in the Upper Devonian of the county is afforded by an imperfect dorsal 

 plate from Chudleigh, preserved in the collection of the British Museum, 

 and probably referable to the typical genus Coccosteus.^ It is one of the 

 numerous specimens from the west of England presented to the national 

 collection by the late Mr. J. E. Lee of Caerleon. 



' ^uart. Joum. Geol Sec. xxxii. 278. ^ Ibid. x. 257. 



" See A. Smith Woodward, Cat. Foss. Fid. Brit. Mus. ii. 116. 



* See E. R. Lankester, ^art. Joum. Geol. Soc. xxiv. 546, and Woodward, op. cit. 175. 



" See Woodward, op. cit. 293. 



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