PSAMMODONTIDJE. 
101 
transverse rugae. Complete dentition apparently consisting of a 
median pair of teeth, generally broader than long, with a lateral 
pair considerably longer than broad. 
As shown by J. W. Davis, loc. Git., the teeth of this species vary 
much in form—some having a convex coronal surface, some concave ; 
some broader than long, raised at each narrow extremity, others 
longer than broad, with similarly raised lateral margins ( C . canali- 
culatus, M‘Coy); some nearly triangular in shape. The differences 
between these various forms are as great as many considered to be 
of specific value in other cases ; but all the varieties, except one, are 
fortunately unnamed, and it seems advisable, upon present evidence, 
to recognize only a single species. 
Form. Sf Loc. Carboniferous Limestone: Ireland, Scotland, Eng¬ 
land, Wales, Belgium, Bussia. 
(i.) Co. Sligo, Ireland; Enniskillen Collection. 
P. 2555. Type specimen described and figured by Agassiz, loc. cit. 
p. Ill, pi. xix. fig. 15; Easky. 
P. 4163. Crown of much abraded broad tooth; Ballisodere. 
(ii.) Armagh, Ireland ; all from the Enniskillen Collection, 
unless otherwise stated. 
P. 2556. Large transversely elongated tooth, figured by J. W. Davis, 
loc. cit. pi. lvi. fig. 1. 
P. 2562. Large tooth, longer than broad, figured loc. cit. pi. lvii. 
fig. 6. 
P. 2563. Detached abraded crown, figured loc. cit. pi. lvii. fig. 5. 
P. 2561. Abraded small tooth, broader than long, figured loc. cit , 
pi. lvii. fig. 4. 
P. 2559, 60, P. 2564. Lateral teeth, figured loc. cit. pi. lvii. figs. 2, 
3, 7. Upon the original label the third of these teeth is 
said to have been obtained from the Orton Scar Lime¬ 
stone, Bavenstone Dale, Westmoreland. 
P. 2566. Thirty-four teeth of large size, more or less perfect. 
P. 2567. Eour fragmentary teeth, with strong rugose ornament, 
said to have been found associated. 
P. 4162. The finely ornamented crowns of seven broad teeth. 
