100 
SELACHII. 
root much thicker than the crown, and readily detached from the 
latter. Coronal surface generally marked by transverse rugae. The 
exterior postero-lateral angle of each tooth is somewhat produced 
backwards, to ensure more firm articulation with the succeeding 
tooth; and there appear to have been not more than four antero¬ 
posterior rows in each jaw—a middle pair and a lateral, without 
any median azygous series. 
Psammodns sragosus ? Agassiz. 
1838. Psammodus rugosus, L. Agassiz, Poiss. Foss. vol. iii. p. Ill, 
pi. xii. figs. 14-18, pi. six. fig. 15. 
1838. Psammodus porosus, L. Agassiz, tom. cit. p. 112, pi. xiii. figs. 1-18. 
1843. Psammodus rugosus , J. E. Portlock, Rep. Geol. Londonderry, 
p. 465, pi. xiv a, fig. 1. 
1843. Psammodus porosus, J. E. Portlock, op. cit. p. 466, pi. xiv a , fig. 2. 
1844. Psammodus rugosus, L. G. de Koninck, Descr. Anim. Foss. Terr. 
Carb. Belg. p. 616, pi. lv. fig. 4. 
1844. Psammodus porosus, L. G. de Koninck, op. cit. p. 616, pi. liii. fig. 8. 
1848. Psammodus canaliculatus, F. M‘Coy, Ann. & Mag. Nat. Hist. [2] 
vol. ii. p, 122. 
1855. Psammodus canaliculatus, F. M‘Coy, Brit. Palaeoz. Foss. p. 643, 
pi. 3 Gr, fig. 12. 
1855. Psammodus rugosus, F. M‘Coy, op. cit. p. 644. 
1855. Psammodus rugosus, var. porosus, F. M‘Coy, op. cit. p. 644. 
1860. Psammodus porosus, E. d’Eichwald, Lethsea Rossica, vol. i. 
p. 1547. 
1862. Psammodus rugosus, Morris & Roberts, Quart. Journ. Geol. Soc. 
vol. xviii. p. 102. 
1864. Psammodus rugosus, H. Romanowsky,Bull. Soc. Imp. Nat. Mos- 
cou, pt. ii. p. 158, pi. iii. figs. 3, 5. 
1864. Psammodus porosus, IL. Romanowsky, tom. cit. p. 158, pi. iii. fig. 4. 
1875. Psammodus porosiis, W. H. Baily, Figs. Char. Brit. Foss. p. 120, 
pi. xli. fig. 9. 
1877. Psammodus rugosus, R. Etheridge, jun., Geol. Mag. [2] vol. iv. 
p. 308, pi. xiii. figs. 7-9. 
1878. Psammodus porosus, L. G. de Koninck, Faune Calc. Carb. Belg. 
pt. i. p. 41, pi. v. figs. 1-5. 
1883. Psammodus rugosus, J. W. Davis, Trans. Roy. Dublin Soc. [2] 
vol. i. p. 459, pis. lvi., lvii. 
1884. Psammodus rugosus, J. W. Davis, Quart. Journ. Geol. Soc. vol. xl. 
p. 629. 
1886. Psa?nmodus rugosus, J. W. Davis, Geol. Mag. [3] vol. iii. p. 156. 
Type. Detached teeth; Bristol and British Museums. 
A very large species. Teeth comparatively thick; the coronal 
surface in unworn specimens marked by numerous strong, coarse, 
