e->- e *- r- v- crjr < >-» - 
y. - c~/? O'^s-S^ ClXXXtV. / a „. rqz z./y./Ti- 
CESTRACIONTIDiE. 
331 
P. 5834. Imperfect small tooth; Craie phosphatee, Ciply, near 
Mons, Belgium. 
Presented by Mons. A. Houzeau de Lehaie, 1888. 
Several teeth of Synechodus, from the Lower Planerkalk of Weiss- 
kirchlitz, Bohemia, have been described by A. E. Reuss, Yerstein. 
bohm. Er eideform, pt. ii. 1846. They have received the following 
seven names, but cannot be regarded as representing so many 
species :—Hybodus bronnii (p. 97, ph xxiv. fig. 26, pi. xlii. fig. 7); 
H. 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); H. regu - 
laris (p. 98, pi. xxi. fig. 11); H. serratus (p. 98, pi. xxi. figs. 14,15); 
and H. tenuissimus (p. 98, pi. xxi. figs. 16, 17). Of all of these, 
figures are also given by A. Eritsch, Rept. u. Eische bohm. Kreide- 
form. 1878, p. 6, figs. 7, 8 (woodcuts), p. 13, figs. 28-32 (woodcuts) ; 
and H. gracilis is noticed by C. E. Eischer, Allg. deutsch. Naturh. 
Zeitung, n. s. vol. ii. (1856), p. 140, pi. ii. fig. 35. H. regularis and 
H. gracilis are considered to be the young of (i Otodus sulcatus” 
by H. B. Geinitz, Paheontogr. vol. xx. pt, i. (1875), p. 294, and by A. 
Eritsch, op. cit. 
Grans. CESTRACION, Cuvier. 
[Regne Animal, vol. ii. 1817, p. 129.] 
hr , vf 
Syn. Heterodontus , A. I), de Blainville, Bull. Soc. Philom. 1816, p. 121 l . 
Tropidodus, T. Gill, Proc. Acad. Nat. Sci. Pkilad. 1862, p. 489. 
Gyropleurodas, T. Gill, loc. cit. p. 489. 
Drepanephorus, Sir P. Egerton, Eigs. & Descrips. Brit. Organic 
space between the pectorals and pelvics, the second in advance of 
the anal, llouth 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 large 
dermal hooks upon the claspers of the male. Vertebrae well deve¬ 
loped, asterospondylic. 
1 This name being prior to Cestradon, it is frequently employed in syste¬ 
matic works; it is, however, preoccupied by Heterodon , Palisot de Beauvois (in 
Latreille, Rept. vol. iv. 1800, p. 32), applied to a recent Ophidian. 
