216 
SELACHII. 
Strebloclus oblongus by L. G. de Koninck (Faune Calc. Carbf. Belg. 
pt. i. p. 55, pi. vi. fig. 22) also appears to be referable to Deltopty- 
cJiius. 
Genus DIPBAGOBBS Davis. 
[Quart. Journ. Geol. Soc. vol. xl. 1884, p« 632.] 
An uncertain genus founded upon a fragment of a dental plate 
resembling the original of PI. VI. fig. 27, apparently only differing 
from the supposed lower dental plates of D el topty chius in the re¬ 
markable extension of the antero-lateral border indicated by the 
plain line. 
Diplacodus tmlboides, Davis. 
1884. Diplacodus bulboides, J. W. Davis, loc. cit. p. 633, pi. xxvii. fig. 20. 
Type. Fragment of dental plate ; Horne Collection, York Museum. 
The single known species. 
Form. <$f Loc. Upper Carboniferous Limestone : Yorkshire. 
P. 4913. Dental plate shown of the natural size in PI. VI. fig. 27 : 
Yoredale Pocks, Wensleydale. The coronal surface of the 
antero-lateral extension, shown in outline, is covered by 
matrix, but appears to be certainly of the form indicated. 
Horne Coll. 
Genus CYRTONOBUS, Davis. 
[Quart. Journ. Geol. Soc. vol. xl. 1884, p. 630.] 
A doubtful and provisional genus founded upon triangular dental 
plates very suggestive of those of DeUgpty chius, but exhibiting a 
large rounded coronal prominence anterc-laterally, expanded into a 
wing postero-laterally ; the root also extending considerably beyond 
the crown outwardly. The type species is Cyrtonoclus gibbus , Davis 
(loc. cit. p. 631, pi. xxvii. figs. 1, 6), from the Yoredale Pocks of 
Wensley dale, Yorkshire; and it maybe noted that the published 
figures of the plates are so arranged that the antero-lateral mar¬ 
gin is directed upwards, and the postero-lateral downwards. 
Cyrtonodus liornei, sp. nov. 
Type. Detached dental plate ; British Museum. 
1 This name is preoccupied (Diplacodon, O. 0. Marsh, Amer. Journ. Sci. [3] 
vol. ix. 1875, p. 246), but being only provisional, it may be retained until further 
evidence of the nature of the teeth is discovered. 
