PETALODONTIDiE. 
35 
Teeth having the crown so much reflexed and thickened, that the 
complete dentition forms an exclusively tritoral surface. There are 
three principal rows of teeth, diminishing greatly in size towards 
the front of the mouth ; and one or two smaller rows occur on each 
side, having the summit of the crown less bent and thickened than 
the others. The body is covered with fine, smooth shagreen granules, 
largest apparently on the inferior aspect of the head. 
As recognized by K. A. von Zittel 1 , the interpretation of the 
arrangement of the dentition of Janassct proposed by Hancock and 
Howse 2 is undoubtedly erroneous. 
Janassa bitrnninosa (Schlotheim). 
1762. Figure in Dresdinisches Magazin, vol. ii. pt. 4 (FT. B. Geinitz). 
1820. Trilobites bituminosus, E. Schlotheim, Petrefaktenk. p. 39. 
1823. Trilobites bituminosus, E. Schlotheim, Nachtrag Petref. pt. ii. 
pp. 39, 87, pi. 22. fig. 9. 
1832. Janassa angulata, Gf. Munster, Beitr. Petrefakt. i. p. 67, pi. iv. 
figs. 1, 2. 
1832. Janassa humboldi, G. Miinster, op. cit. i. p. 122, pi. xiv. fig. 4. 
1832. Janassa bituminosa, G. Miinster, op. cit. i. p. 122. 
1839. Acroclus larva, L. Agassiz, Poiss. Foss. vol. iii. p. 147, pi. 22. 
- figs. 23-25. 
1839. Janassa angulata, G. A. Kurtze, Dissert. Petrefakt, Mansfeld, 
' p. 20. 
1839. Janassa Jiumboldti, G. A. Kurtze, op. cit. p. 20. 
1840. Janassa angulata, G. Miinster, op. cit. iii. p. 122, pis. iii. & iv. 
fig. 5 a. 
1840. JDictea striata, G. Miinster, op. cit. iii. p. 124, pis. iii. & iv. figs. 1-4, 
pi. viii. figs. 3, 4, 6-10. 
1840. Janassa angulata, F. Germar, Verstein. Mansfeld Kupferschief. 
p. 26, fig. 15. 
1842. Janassa clictea, G. Miinster, op. cit. v. p. 38, pi. xv. figs. 10-16. 
1843. JDictea striata—Act'odus larva, L. Agassiz, op. cit. vol. iii. p. 376. 
1843. Bgzenos latipinnatus, G. Miinster, op. cit. vi. p. 50, pi. i. fig. 2. 
1851-6. Janassa angidata, F. Boemer, Bronn’s Letn. geogn. 3rd edit. 
vol. i. p. 717, pi. ix 4 . fig. 13. 
1851-6. JDictea striata, F. Boemer, tom. cit. p. 718. 
1861. Janassa bituminosa, H. B. Geinitz, Dyas, p. 24, pi. iv. fig. 5, pi. v. 
figs. 1-4. 
1870. Janassa bituminosa, A. Hancock & B. Howse, Ann. & Mag. Nat. 
Hist. [4] vol. v. p. 47, pis. ii., iii. 
1887. Janassa bituminosa, K. A. von Zittel, Handb. Palaeont. vol. iii. 
p. 98. 
1 Handb. Palaeont. vol. iii. (1887), p. 98. 
2 Ann. & Mag. Fat. Hist. [4] vol. v. (1870), p. 47, pi. ii. 
