68 
ACTINOPTEKYGII. 
Sargodon tomicus, Plieninger. 
1847. Sargodon tomicus, T. Plieninger, Wurth Jahresh. vol. iii. p. 165, 
pi. i. figs. 5-10. 
1858. Sargodon tomicus, F. A. Quenstedt, Der Jura, p. 35, pi. ii. figs. 34, 
35 (P figs. 36-38). 
Type. Teeth; Stuttgart Museum. 
The type species, known only by detached teeth, which sometimes 
measure 0*005 in the breadth and in the depth of the crown. 
Dental crown robust, arched from side to side and the concavity 
probably being innermost; cutting-edge smooth, usually obliquely 
truncated by wear. Foot not much compressed, usually nearly 
quadrangular in section, but with a shallow median longitudinal 
groove on its supposed inner face. ^^ 
Form, fy Loc. Bhsetic: Wiirtemberg|and England. 
41288. Tooth in bone-bed ; Axminster. Purchased , 1869. 
P. 7401. Three specimens; Aust Cliff, near Bristol. 
History unknown. 
P. 3930. Fine tooth ; Aust Cliff. EnnisTcillen Coll. 
Genus COLOBODUS, Agassiz. 
[Poiss. Foss. vol. ii. pt. ii. 1844, p. 237.] 
Syn. Asterodon, G. von Munster, Beitr. Petrefakt. pt. iv. 1841, p. 140. 
Omphalodus, H. von Meyer, Neues Jakrb. 1847, p. 574. 
Nephrotus, H. von Meyer, Palseontogr. vol. i. 1851, p. 243. 
Thelodus, E. E. Schmid, Nova Acta Acad. Cses. Leop.-Car, 
vol. xxix. no. 9, 1861, p. 27 (in part). 
j Eupleurodus, G. Giirich, Zeitschr. deutsch. geol. Ges. vol. xxxvi. 
1884, p. 142. 
Hactiylolepis, H. Kunisch, ibid. vol. xxxvii. 1885, p. 594. 
An imperfectly definable genus, not yet satisfactorily distinguished 
from Lepiclotus . The form and proportions of the head and trunk, 
dentition, squamation, and the situation of the fins seem to be as in 
Lepidotus. In most species, however, the teeth are mammillated 
and more or less striated, while their arrangement has not yet been 
definitely proved to agree with that in the last-named genus ; the 
overlapped border of the flank-scales is of uniform width, and not 
produced at the angles ; while the dorsal and anal fins seem to be 
relatively more elevated than in Lepidotus, with smaller and more 
regular fulcra. The gular plate has not been discovered. 
The genus Coloboclus was originally founded upon a fragment of 
dentition from the Muschelkalk of France, and the above state- 
