208 
SELACHIT. 
Cochliodus latus, Leidy. 
1857. Cochliodus lotus , J. Leidy, Trans. Amer. Phil. Soc. [2] vol. xi. 
p. 88, pi. v. fig. 17. 
I860. Helodus ( Cochliodus) nobilzs, Newberry & Worthen, Pal. 
Illinois, vol. ii. p. 89, pi. vii. figs. 1-4, pi. viii. fig. 1. 
1886. Chitonodus latus, St. John & Worthen, Pal. Illinois, vol. vii. 
p. 112. 
Type. Portion of “ lower ” dental plate. 
A comparatively large species, the posterior “ lower ” dental plate 
having an antero-posterior measurement of 0’075. The large ridge 
of the posterior ‘‘lower ” plate relatively narrow, with a tendency 
towards angulation, and not quite attaining the inner margin ; 
coronal surface slightly wrinkled at right angles to the inner mar¬ 
gin. Anterior “ lower ” dental plate with low ridge and feeble 
plications. Opposing dental plate equal in antero-posterior extent 
to the two teeth just described, and having the characters of the so- 
called Streblodus. 
In the fine specimen described by Newberry and Worthen, loc. 
cit ., there are several scattered series of iA?oc?ws-shaped teeth in 
association with the large teeth. 
Form. Sf Loc. Keokuk Limestone (Lower Carboniferous): Illinois, 
TJ.S.A. 
P.2430. An almost perfect posterior “lower tooth ; Warsaw. 
Illinois. Enniskillen Coll. 
The following species have also been founded upon detached 
teeth, but there are no examples in the Collection :— 
Cochliodus costatus , Newberry & Worthen, Pal. Illinois, vol. iv. 
(1870), p. 364, pi. iii. figs. 10, 12.—Burlington Lime¬ 
stone ; Iowa. 
Cochliodus leidyi, St. John & Worthen, op. cit. vol. vii. (1883), 
p. 127, pi. vii. figs. 11-16.—Chester Limestone; Illinois. 
[In this species are also included Streblodus- like teeth 
and anterior Helodont teeth.] 
Cochliodus tenuis , L. G. de Koninck, Paune Calc. Carbf. Belg. 
pt. i. (1878), p. 58, pi. vi. fig. 15.—Lower Carboniferous 
Limestone; Soignies, Tournai. 
Cochliodus van hornii, St. John & Worthen, op. cit. vol. vii. p. 120, 
pi. vii. figs. 1-10.—St. Louis Limestone; Illinois, Missouri, 
and Iowa. [Streblodus- like teeth are hypothetically 
assigned to the upper jaw, and Helodus-like teeth to the 
more anterior region.] 
