198 
SELACHII. 
Deltodus rugosus, sp. nov. 
Type. Upper and lower dental plates, shown in PI. VI. figs. 21, 
22 . 
A very small species, the maximum transverse measurement of 
the supposed lower posterior dental plate being about 0*011. Trans¬ 
verse ridges and furrows of the dental crown fine, not always con¬ 
tinuous, more or less wavy. Posterior “ lower ” dental plate notably 
elongated in an antero-posterior direction, the gently rounded 
coronal elevation extending from the outer to the inner margin not 
immediately adjoining the antero-lateral border. 
Form , Log. Carboniferous Limestone : Shropshire. 
42186, 36193. Type specimens shown, of twice the natural size, in 
PI. VI. figs. 21, 22, the first being an “ upper ” dental 
plate, the second a “ lower ” ; Oreton. 
Baugh Coll., and Purchased, 1861. 
42186 a. Imperfect “ upper ” dental plate ; Oreton. Baugh Coll. 
42188 b, 42225. Four imperfect “ lower ” dental plates ; Oreton. 
Baugh Coll. 
Deltodus concha (Trautschold). 
1874. Pcecilodus concha , H. Trautschold, Mem. Soc. Imp. Nat. Moscou, 
vol. xiii. p. 290, pi. xxviii. fig. 6, pi. xxix. fig. 10. 
1874. Pcecilodus limbatus, II. Trautschold, tom. cit. p. 290, pi. xxviii. 
fig. 7. 
Type. Detached tooth. 
A comparatively small species, the maximum transverse measure¬ 
ment of the supposed lower posterior dental plate being about 0*016. 
Transverse ridges and furrows of the dental crown few, large, 
rounded. Posterior “ lower ” dental plate (“ Poeciloclus limbatus ) 
slightly elongated antero-posteriorly, the prominent elevation ex¬ 
tending from the outer to the inner margin very broad, gently 
rounded, immediately adjoining the antero-lateral margin. Anterior 
“ lower ’’ dental plate (“ Poeciloclus concha ”) rapidly widening 
inwardly. 
Form. Sf Loc. Carboniferous Limestone: Government of Moscow, 
Russia. 
P. 5115. Three anterior dental plates ; Mjatschkowa. 
Purchased , 1886. 
