216 
SELACHir. 
Strehlodus oblongus by L. 0. do Koninck (Faune Calc. Carbf. Folg. 
pt. i. p. 55, pi. vi. fig. 22) also appears to be referable to Deltojiiy- 
ehius. 
Genus DIPLACODUS Davis. 
[Quart. Journ. Geol. See. vol. xl. 1884, p. 632.J 
An uncertain genus founded upon a fragment of a dental plate 
resembling tbo original of I’l. VI. fig. 27, aiiparently only differing 
from the supposed lower dental plates of Bellojitychitts in the re- 
markable extension of the antero-laterul border indicated by the 
plain line. 
Diplacodus bulboides, Davis. 
1884. Diplacodus hulhoides, J. VV. Davis, luc. ci7.p. 0.33, pi. xxvii. fig. 20. 
Type. Fragment of dental plate ; Horne Collection, York Museum. 
The single known species. 
Form. ^ hoc. Upper Carboniferous Limestone : Yorkshire. 
P. 4913. Dental plate shown of the natural size in PI. VI. fig. 27 ; 
Yoredale Rocks, Wenslcydule. The coronal surface of the 
antero-lateral extension, shown in outline, is covered by 
matrix, but appears to be certainly of tlio form indicated. 
Horne Coll. 
Genus CYRTONODUS, Davis. 
[Quart. Journ. Geol. 8oc. vol. xl. 1884, p. 630.] 
A doubtful and provisional genus founded upon triangular dental 
plates very suggestive of those of Deltoptyrhius, but exhihiling a 
largo rounded coronal prominence antero-lateral ly, expanded into a 
wing po.stero-laterally ; the root also extending cou.siderably beyond 
the crown outwardly. The type species is Uyrtonodvs yihhus, Davi.s 
{loc. cii. p. 031, pi. xxvii. figs. 1, 6), from the Yoredale Rocks of 
Wensleydale, Yorkshire ; and it may bo noted that the published 
figures of the plates are so arranged that the antero-lateral mar- 
gin is directed upwards, and the postero-latcrul downwards. 
Cyrtonodus hornei, sp. nov. 
Type. Detached dental plate ; British Museum. 
‘ Tin’s name is preoccupied {Diplacodmi, O. 0. Marsh, Amer. Joiirii. Sci. [3] 
vol. ix. 187.3, p. 246), but being only provisional, it may be retained until Curtber 
evidence oC the nature of the teeth is discovered. 
