108 
SELACHII. 
Moscou, vol. xiii. (1874), p. 271, pi. xxvii. fig. 12; Helodus, 
P. Semenow & W. yon Moller, Bull. Acad. Imp. Sci. St. 
Petersb. yol. yii. (1864), p. 235, pi. i. fig. 9.—Lower 
Carboniferous Limestone (L. G. de Koninck) or Upper 
Devonian (Trautschold) ; Government of Toula, Bnssia. 
Psammodus lovianus, St. John & Worthen, tom. cit. p. 207, pi. xiv. 
figs. 7-9.—Burlington Limestone; Iowa, Illinois. 
Psammodus plenus, St. John & Worthen, tom. cit. p. 213, pi. xvi. 
figs. 1-4, pi. xvii. figs. 1-4.—St. Louis Limestone; Mis¬ 
souri, Illinois, Michigan. 
Psammodus reticulatus, Newberry & Worthen, tom. cit. p. 109, 
pi. xi. fig. 5; St. John & Worthen, tom. cit . p. 224, pi. xix. 
figs. 3, 5.—Chester Limestone; Illinois. 
Psammodus spring eri, St. John & Worthen, tom. cit, p. 202, pi. xx. 
figs. 4-11.—Upper Burlington Limestone; Iowa, Illinois. 
Psammodus tumidus, St. John & Worthen, tom. cit. p. 205, pi. xiv. 
figs. 1-4.—Upper Burlington Limestone ; Iowa, Illinois. 
Psammodus turgidus, St. John & Worthen, tom. cit. p. 206, pi. xv. 
fig. 4.—Upper Burlington-Keokuk Limestone; Iowa. 
It is also uncertain whether the tooth described under the 
following name may not be referred to a lateral position in the jaw 
of j Psammodus :— 
Solenodus crenulatus , H. Trautschold, Nouv. Mem. Soc. Imp. Nat. 
Moscou, vol. xiii. (1874), p. 293, pi. xxviii. fig. 11.— 
Carboniferous Limestone; Moscow, Kussia. 
An indeterminable tooth from the Rhsetic of Stuttgart, certainly 
not of Psammodus , is described under the name of P. orbicularis , 
Plien. (Meyer & Plieniuger, Pal. Wiirttemb., 1844, p. 117, pi. x. 
%. 24). 
Genus ARCH^OBATIS, Newberry. 
[Ann. New York Acad. Sci. vol. i„ 1878, p. 190.] 
“ Dentition flat and pavement-like ; teeth of large size, thick and 
massive, in several rows, the different series arched and increasing 
in size from behind forward; under surfaces somewhat excavated 
to fit the curvature of the cartilaginous jaw; upper third of teeth 
formed by a coat of enamel, transversely corrugated and punctate/’ 
Archceobatis gigas, J. S. Newberry, loc. cit. p. 191; also in Ann. 
Bep. Geol. Surv. Indiana, 1879, p. 34^ ; —St. Louis Lime¬ 
stone : Greencastle, Indiana. /LA 
