COCHI.IODOXTIDJi. 
177 
more or loss crenulatcd. Other side-teeth with gently rounded 
crowns and crcnulated margins ; symphysial teeth smaller and 
feebly prehensile. 
A considerable portion of the dentition of the type species of the 
genus has been described by It. H. Traquair It appears that there 
are two forms of the large dental plates, one probably in each jaw ; 
and it seems likely that there was originallj' at least one series of 
small teeth situated posteriorly to these. The “upper” dental 
plate has a relatively greater antero -posterior measurement than 
the “ lower,” and is less curved round the supporting cartilage. 
Psephodus magnus (M-Coy). 
184.S. Cochliodus 7nngnux,'L,. Aga-ssiz, Poiss, Foss. vol. iii. p. 174 (name 
only). 
1844. Jlelvdus planus, L. .Vgaasiz, cit. p. 17.3 (name only). 
1843. Ilelodiis didgmus, L. Aga.ssiz, tom. cit. p. 173 (name only). 
1843. Coehliodtts maguHs, J. E. Portlock, Rep. Geol. Londonderry, 
p. 4C0, pi. .xiv. <z. fig. 4 (figure only). 
1843. Ilelodus planus= CoaMiudu,s nuifpius, .1. E. Portlock, np. cit. p. 4(12. 
1855. Cochliodus magnus, F. 11‘Ooy, Rrit. Palseoz. Foss. p. 022. 
18.55. IModus planus, F. M'Coy, op. cit. p. (531, pi. 3 i. figs. 12-15. 
1855. Jlelodns didgmus, F. M'Coy, op. cit. p. 030, pi. 3 1 , figs. lA 20 
(in part). 
1855. Jlelodus lavissimns, F. M‘0oy, op. cit. p. 630 (in part). 
1855. Ilelodus mdis, F. M‘Coy, op. cit. p. 031, pi. 3 k. fig. 4. 
1802. Psephodus magnus, Morri.s & Roberts, Quart. Journ. Geol. Soc. 
vol. xviii. p. 101 (name only). 
(?) 1878. Psephodus magnus, L. G. do Koniack, Faune Calc. Carbf. 
Belg. pt. i. p. (50, pi. iv. fig. 10 (non figs. 14, 15, 17). 
(?) 1878. Tomodus craigi, L. G. de Koniuck, op. cit. pt. i. p. 61, pi. iv. 
fig. 8, pi. vi. figs. 18, 10. 
1883. Psephodus magnus, .1. W. Davis, Trans. Roy. Dublin Soc. [2] 
vol. i. p. 4.30, pi. Iv. figs. 1-14. 
1883. Lophodus Icecissimus, .1. W. Davis, totn. cit. p. 404, pi. li. fig. 18 
(in part). 
1883. Lophodus didgmus, J. W. Davis, tom. cit. p. 407, pi. li. fig. 21 (in 
part). 
1883. Ilelodus rudis, .1. \V. Davis, tom. (it. p. 457, pi. lix. fig. 11. 
1883. Selachian Fi.sh, J. Coutts, Trans. Geol. Soc. Glasgow, vol. vii. 
p. 104. 
1885. Psephodus magnus, R. II. Traquair, Trans. Geol. Soc. Glasgow, 
vol. vii. p. 392, pi. xvi. ; and Geol. Mag. [3] vol. ii. p. 337, 
pi. viii. 
1886. Psephodus magnus, J. W. Davis, Geol. Mag. [3] vol. iii. p. 151. 
'■ Trans. Gteol. Soa Glasgow, vol. vii. (1884), p. 396, pi. xvi. ; also Geol. Mag. 
[3J vol. ii. (1885), p. 337, pi. viii. 
