PETALODONTID.E. 
49 
Phil. Soc. [2] vol. si. (1857), p. 89, pi. v. figs. 24-26.— 
Lower Carboniferous, Illinois; and St. Louis Limestone, 
Missouri. 
Chomatodus lamelliformis , J. W. Davis, Quart. Journ. Geol. Soc. 
vol. xl. (1884), p. 625, pi. xxvii. fig. 23.—Yoredale Rocks; 
Wensleydale, Yorkshire. 
Chomatodus loriformis, Newberry & Worthen, op. cit. vol. ii. p. 58, 
pi. iii. fig. 19.—Keokuk Limestone; Illinois, 
Chomatodus molaris, Newberry & Worthen, op. cit. vol. ii. p. 56, 
pi. iii. fig. 17.—Keokuk Limestone; Illinois. 
Chomatodus multiplicatus, Newberry & Worthen, op. cit. vol. ii. 
p. 57, pi. iii. fig. 18.—Burlington Limestone; Iowa. ? Also 
Tanaoclus multiplicatus, L. G. de Koninck, Paune Calc. 
Carbf. Belg. pt. i. 1878, p. 53, pi. vi. figs. 10,11.—Lower 
Carboniferous Limestone; Tournai. 
Chomatodus parallelus, St. John & Worthen, op. cit. vol. vi. p. 358, 
pi. x. a. figs. 3, 4.—Warsaw Beds; Illinois, Missouri. 
Chomatodus pusillus, Newberry & Worthen, op. cit. vol. ii. p. 53, 
pi. iii. fig. 14.—Keokuk Limestone; Illinois. 
Chomatodus sarcululus, Newberry & Worthen, op. cit. vol. iv. p, 356, 
pi. ii. fig. 8.—Burlington Limestone ; Iowa. 
The genus Lisgoclus, St. John & Worthen (op. cit. vol. vi. 1875, 
p. 363), is difficultly definable from Petdloclus. Pour species are 
described— L. curtus (tom. cit. p. 364, pi. x.a. figs. 20-22), L. selluli- 
formis (tom. cit. p. 366, pi. x.a. fig. 16), L. serratus (tom. cit. p. 365, 
pi. x.a. figs. 17-19), and L. affinis (J. S. Newberry, Ann. Rep. Geol. 
Surv. Indiana, 1879, p. 343). The first and third are from the 
Upper Burlington Limestone, Illinois and Iowa; the second and 
fourth from the Upper St. Louis Limestone, Illinois and Missouri. 
• Closely allied also is the genus Calopodus , St. John & Worthen, 
represented by the single species C. apicalis, St. J. & W. (Pal. Ill. 
vol. vi. 1875, p. 403, pi. xii. figs. 16, 17), from the Middle Coal- 
Measures of Iowa. 
Genus CTENOPTYCHIUS* A gassiz. 
[Rech. Poiss. Poss. vol. iii. 1838, p. 99.] 
Syn. Ctenopetalus, J. W. Davis (ex Agass. MSS.), Ann. & Mag. Nat. ^ 
Hist. [5] vol. viii. 1881, p. 426. 
Harpacodus, J. W. Davis (ex Agass. MSS.), loc. cit. p. 426. 
Serratodus , L. G. de Koninck, Paune Calc. Carbf. Belg. pt. i 
1878, p. 53. 
Periprislis, O. St. John, Proc, Amer. Phil. Soc. vol. xi. 1870, 
p. 434. 
