CESTKACIONTIDiE. 
331 
P. 5834. Imperfect small tooth ; Craie phosphatee, Ciply, near 
Mens, Belgium. 
Presented hy Mens. A. Houzeau de Lehaie, 1888. 
Sereral teeth of Synechodus, from the Lower Pliinerkalk of Weiss- 
kirchlitz, Bohemia, have been described by A. E. Reuss, Yerstein. 
bbhm. Kreideform. pt. ii. 1846. They have received the Mowing 
seven names, but cannot be regarded as representing so many 
species: — Hybodus bronnii (p. 97, ph xxiv. fig. 26, pi. xlii. fig. 7); 
S. dispar (p. 98, pi. xxiv. figs. 27, 28) ; H. gracilis (p. 98, pi. xxi. 
figs. 12, 13); H. polyptychus (p. 97, pi. xxi. figs. 9, 10); II. regu- 
la,ri$(p. 98, pi. xxi. fig. 11); H. serratus (p. 98, pi. xxi. figs. 14, 15); 
and II. Unuissimus (p. 98, pi. xxi. figs. 16, 17). Of all of these, 
figures arc also given by A. Fritsch, Kept. u. Fischo bbhm. Kreide- 
form. 1878, p. 6, figs. 7, 8 (woodcuts), p. 13, figs. 28-32 (woodcute) ; 
and II. gracilis is noticed by C. E. Fischer, Allg. deutsch. Naturh. 
Zeitung, n. s. vol. ii. (1856), p. 140, pi. ii. fig. 35. II. regularis and 
II. gracilis are considered to be the young of “ Otedus sulcatus 
by H. B. Geinitz, Palaeontogr. vol. xx. pt. i. (18/5), p. 294, and by A. 
Fritsch, o^j. cit. 
Genus CESTRACION, Cuvier. 
[Eegne Animal, vol. ii. 1817, p. 129.] 
Syn. Heterodontus, A. D. de Blainville, Bull. Soc. Philom. 1816, p. 121 *. 
Tropidodus, T. Gill, Proc. Acad. Nat. Sci. Philad. 1862, p. 489. 
Oyropleurodtis, T. Gill, foe. dt. p. 489. 
Drepanephorus, Sir P. Egerton, Figs. & Descrips. Brit. Organic 
remains (Mem. Geol. Surv. 1872), dec. xiii. no. ix. 
Body moderately elongated ; the first dorsal fin opposite to the 
space between the pectorals and pelvics, the second in advance of 
the anal. Month terminal or nearly so. Dentition (fig. 13), spe- 
cialized ; the anterior teeth small, numerous, cuspidate, generally 
■with at least one pair of lateral denticles ; principal teeth without 
cusps, but relatively broad and flattened, having a slight longitudinal 
keel and a more or less reticulate ornamentation. Dorsal fin-spines 
smooth, the sides covered with a dense layer of ganoine ; posterior 
denticles absent. Shagreen fine ; no cephalic spines ; no lai^ 
dermal hooks upon the claspers of the male. Yertebrae well deve- 
loped, asterospondylic. 
This name being prior to Cesiracion, it is frequently employed in syste- 
matic works ; it Ls, however, preoccupied by Heierodon, Palisot de Beauvois (in 
lAlreille, Bept. vol. iv. 1800, p. 32), applied to a recent Ophidian. 
