184 
SELACHII. 
lively small antero-posterior measurement oi the ‘ upper dental 
plate, are indicated by the following specimens: 
23712. A small dental plate, shown, of the natural size, in PL \ I. 
fig. 17; Lower Carboniferous Limestone, Hook Point, 
Wexford, Ireland. Purchased, 1849. 
P. 227 C. A larger corresponding plate, with prominently-coloured 
transverse bands, shown, of the natural size, in PI. I. 
fig. 18 ; Carboniferous Limestone, Oreton. 
Weaver-Jones GoU. 
The following species have also been founded upon detached 
dental plates, but there are no examples in the Collection : 
Psephodus crenulatus , St. John & Worthen, Pal. Illinois, vol. vii. 
(1883), p. 67 : Aspidoclus crenulatus, Newberry & Worthen, 
Pal. Illinois, vol. ii. (1866), p. 93, pi. viii. figs. 3-11 ; also 
J. S. Newberry, Ann. Rep. Geo-1. Surv. Indiana, 1876- 
78 (1879), p. 341 : Aspidoclus eonvolvtus, Newberry & 
Worthen, tom. cit. p. 94, pi. viii. fig. 12.—Chester Lime¬ 
stone ; Illinois and Kentucky. 
Psephodus dentatus: Heloclus dentatus, H. Romanowsky, Bull. 
Soc. Imp. Nat, Moscou, 1864, pt. ii. p. 159, pi. iii. figs. 12- 
v 16._Lower Carboniferous Limestone; Government of 
Toula, Russia. ? Heloclus dentatus , L. G. de Koninck, 
Faune Calc. Carbf. Belg. pt. i. (1878), p. 40, pi. iv. fig. 18.— 
Lower Carboniferous Limestone; Tournai, Belgium. 
Psephodus indicus, W. Waagen, Pal. Ind. ser. 13, pt. ii. (1880), 
p. 73 , pi. vii.figs. 3,5.—Productus Limestone; Salt Range, 
India. 
Psephodus latus , St. John & Worthen, op. cit. vol. vii. p. 72, pi. ii. 
figs. 1-3.—St. Louis Limestone ; Illinois, Missouri.^ 
Psephodus minor , H. Trautschold, Mem. Soc. Imp. Nat. Moscou, 
vol. xiv. (1879), p. 57, pi. vii. figs. 9, 10 ( non figs. 11, 12). 
—Carboniferous Limestone ; Mjatschkowa, Moscow. 
Psephodus obliquus , St. John & Worthen, op. cit. vol. vii. p. 66, 
pi. i. figs. 1-5.—Kinderhook Limestone ; Iowa. 
Psephodus placenta , St. John tfc 1\ orthen, op. at. vol. vii. p. 69, 
pi. ii. figs. 5-8 : Helodus placenta, Newberry & Worthen, 
op. cit. vol. ii. p. 80, pi. v. fig. 4.—Kinderhook Lime¬ 
stone ; Iowa. 
Psephodus reg ulcer is \ Tceniodus regularis, St. John & Worthen, 
op. cit. vol. vii. p. 77, pi. xiii. fig. 11.—Warsaw Lime¬ 
stone ; Indiana. 
