110 
SELACHlr. 
Type. Upper dental plates; British Museum. 
Teeth very massive, the coronal contour transversely arched, 
especially in the upper jaw. Longitudinal superficial striae well 
marked in unabradcd specimens. Median teeth in the adult rarely 
or never more than five times as broad as long ; lateral teeth much 
longer than broad. 
The specimens figured respectively under the names of M. con- 
ttacius, M. slrialus, and M. toliapicus, by Dixon and Qeinitz, he. cit., 
are examples of the lower dentition of If. clivoni : so also probably 
is the type specimen of M. heteropleurvs, Agassiz. Numerous 
measurements of the tooth at various stages of growth are given 
by the present writer, loc. cit. 
Form. Loc. Barton Clay (Upper Eocene) : Hampshire. Brack- 
Icsham Beds (Middle Eocene) : Sussex. Phosphate Beds (Middle or 
Upper Eocene) : Holmstedt, near Harzburg, Brunswick. (?) Lower 
Eocene : Cuise-Ia-Mottc, Oise, Erance. 
Upper Dentition . — Bracklesham Beds, Bracklesham Bay. 
25614, 25621, 25623, P. 434. Typo specimens figured by Dixon, 
op. cit., and noticed by the present writer, loc. cit. p. 41 . 
DLvon Coll., and (P. 434) Purchased, 1882. 
25644. Abnormal specimen, having the lateral plates in the form of 
irregular parallelograms, referred to by Dixon, op. cit. 
p. 198. Dixon Coll. 
25645-6, 25648-9, 25654. Plates in connected series. Dixon Coll. 
25664. A very fine connected scries of nine median teeth, with two 
lateral rows on each side ; the unworn surface is somewhat 
longitudinally striated and wrinkled. Dixon Coll. 
38839, 38841-46. Plates in connected series. The first specimen 
is noticed by the present writer, loc. cit. p. 41. 
Bowerhanlc Coll. 
P.435, P.437. Six examples. Purchased, 
P. 5384. Four medium-sized specimens. 
Presented by P. E. Coomhe, Esq., 1888. 
P. 1496, P. 1498, P. 1498 a, P.1504 a, P. 1507 c, P. 1509. Twenty 
examples. No. P. 1498 a is noticed by the present writer, 
loc. cit. p. 41. Egerton Coll. 
P. 3044, P. 3044 a-c. Twelve examples. Nos. P. 3044 a, h, are 
noticed by the present writer, he. cit. p. 41 . 
EnnisTcillen Coll. 
