SEMIONOTID^E. 
109 
1854. Lepidotusfittoni,Z. Morris, ibid. p. 331. 
1854. Lepidotus mantelli , J. Morris, ibid. p. 332. 
1860. Lepidotus Jittoni , J. E. Lee, Geologist, vol. iii. p. 458, pi. xii. 
1887. Lepidotus mantelli , W. Branco, Abh. geol. Specialk. Preussen u. 
Tbiiring. Staaten, vol. vii. p. 345, pi. iii. figs. 1, 2. 
1890. Lepidotus mantelli, Woodward & Sberborn, Catal. Brit. Foss. 
Yertebrata, p. 112. 
Type. Portion of fish : British Museum. 
A species attaining a length of about 1 metre. Trunk very 
robust, and head with opercular apparatus occupying about one- 
quarter of the total length of the fish. Maximum width of operculum 
nearly two-thirds as great as its depth, and equalling about one- 
third the length of the head; frontal profile very slightly bent and 
snout acute. External bones more or less rugose or tuberculated ; 
parietal bones much less than half as long as the frontals, which 
are three times as long as their maximum width, very narrow in 
front, and united throughout their length by a nearly straight 
median suture; mandibular symphysis very robust, the dentary 
bone being much horizontally extended to support the large denti¬ 
gerous splenial. Inner teeth very short and stout, the majority, 
when unworn, with a slightly acuminate crown, but always smooth ; 
marginal teeth also robust; splenial teeth in five (sometimes six) 
irregular concentric series increasing in size within; pterygo¬ 
palatine teeth in three (sometimes four) longitudinal series increasing 
in size within; vomerine dentition increasing in size backwards, the 
anterior teeth very irregular, in about four longitudinal series, the 
largest posterior teeth comprising two pahs with one median tooth 
in advance. Ping-vertebrae present in the adult. Ein-fulcra very 
large; pelvic fins arising nearer to the pectorals than to the anal; 
anal fin arising opposite the hinder extremity of the dorsal. Scales 
smooth, those on the flanks often crimped towards their hinder 
border and more or less coarsely serrated, those of the lateral line 
deeply notched, and all showing oblique ridges when worn; prin¬ 
cipal flank-scales somewhat deeper than broad; dorsal ridge-scales 
inconspicuous but acuminate. 
Form. <Sf Log. Wealden : S.E. England and H. Germany. 
2456. Hinder portion of head with part of the abdominal region. 
described and figured by Agassiz, tom . cit. p. 263, pi. xxx. c. 
fig. 1, and to be regarded as the type specimen; Heath- 
field. The drawing is very unsatisfactory, and there is no 
indication of the few coarse denticulations exhibited by 
some of the scales. The left hyomandibular and meta- 
