OSTEOGLOSSIDJE. 
83 
Plethodus pentagon, A. S. ^Voodward. 
1899. Plethodus 'pentagon^ A. S. Woodward, Ann. Mag. Nat. Hist. [7] 
Yol.-iii. p. 356, pi. xiii. figs. 5-7. 
Type. Lower dental plate ; British Museum. 
A smaller species, the lower dental plate attaining a length of 
about O’Ooo with a maximum breadth of 0-04. Lower dental 
plate elongated, pentagonal in shape, widest near the pointed end, 
and the border of the truncated end slightly excavated ; grinding 
surface slightly convex. Supposed upper dental plate quadrangular. 
No bones of this species have hitherto been identified. 
Form. Log. Turonian : S.E. England. 
41716 a. Lower dental plate, being the type specimen describe 
and figured loc. cii. p. 356, pi. xiii. fig. 5; Lower Chalk, 
Burham, Kent. TouJmin Smith Coll. 
47947. Pointed end of lower dental plate, figured loc. cit. pi. xiii. 
fig. 6; Burham. Presented hy the Hon. Robert 
Marsham, 1877. 
35874. Imperfect abraded lower dental plate, the truncated end 
exhibiting a deep accidental cleft; Lower Chalk, Dover. 
Purchased, 1861. 
P. 2693. Two fragments; Lower Chalk, Lewes. Ennis'killen Coll. 
P. 5626. Supposed upper dental plate, described and figured loc. cit. 
p. 357, pi. xiii. fig. 7; Lower Chalk, Kent. Deferred to 
Thryptodus sp. by E. B. Loomis, Palaeontogr. vol. xlvi. 
(1900), p. 235. Harford Coll. 
49816. Portion of similar plate; Lower Chalk, Dorking, Surrey. 
Capron Coll. 
Plethodus oblongus, Dixon. 
1850. Plethodus oblongus, F. Dixon, Geol. Sussex, p. 366, pi. xxxii.^ 
fig. 4. 
1899. Plethodus oblongus, A. S. Woodward, Ann. Mag. Nat. Hist. [7] 
vol. iii. p. 357, pi. xiv. 
Type. Lower dental plate ; Brighton Museum. 
A very small species, the lower dental plate about 0'02 in length, 
olongated and irregularly ovoid in shape, the broader end gently 
rounded, the narrower end truncated; grinding surface of this 
plate slightly convex. 
A small skull in the Brighton Museum, described and figured by 
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