PYCXODONTIDJi. 
259 
to a space considerably separated throughout its extent from the 
thin oral border of the bone, comprising one principal series of 
teeth, flanked within by at least one small series and outside by 
two or more small series. Scales ornamented with reticulating 
rugse. 
This amended definition is given on the assumption that the so- 
called Gyrodus angustus , Agassiz, belongs to the same genus as 
Pycnodus subclavatus, Agassiz. The spfienial bone in the first- 
named species differs from that of all other known P) r cnodonts in 
its wide, toothless margin ; but neither in the so-called Pycnodus 
subclavatus nor in any of the associated species has the imperfect 
nature of the specimens yet permitted the observation of this 
feature. Future discoveries must determine whether or not the 
arrangement here adopted is justifiable. 
The splenial dentition of Anomoeodus is arranged as in Mesoclon , 
but the form of the splenial bone itself is quite different from that 
of the last-named genus, being similar to that of Pycnodus. 
Anomoeodus subclavatus (Agassiz). 
1799. Figures by Faujas St. Fond, Hist. Nat. Mont. St. Pierre, Maes- 
tricht, pi. xviii. fig. 8, pi. xix. fig. 4. 
1833-44. Pycnodus subclavatus, L. Agassiz, Poiss. Foss. vol. ii. pt. i. 
p. 17, pt. ii. p. 198, pi. lxxii. a. fig. 59. 
1848-52. Pycnodus, P. Gervais, Zool. et Pal. Franf. pi. lxix. 
fig. 23. 
1872. Pycnodus cretaceus, H. E. Sauvage ( errore), Bibl. £cole Hautes 
Etudes, vol. v. art. 9, p. 13, pi. i. figs. 3-6. 
1887. Ccelodus subclavatus, K. A. von Zittel, Handb. Pakeont. vol. iii. 
p. 249. 
1887. Anomoeodus subclavatus, H. Forir, Ann, Soc. G6ol. Belgique, 
vol. xiv. M6m. p. 25, pi. i. fig. 1. 
Type. Principal splenial teeth ; Paris Museum of Natural History. 
The type species, known only by the splenial dentition. Teeth 
of the principal series on the splenial bone slightly arcuated, tapering 
and turned forwards at the inner extremity, attaining a breadth 
more than three times as great as their length ; those of the single 
inner series very small and rounded, irregularly arranged ; flanking 
teeth in four irregular series, these mostly smooth and together not 
equalling in width the principal series, the innermost teeth slightly 
broader than long, the next nearly similar, and the two outermost 
series insignificant. 
A good figure of this form of dentition is published by Forir, loc. 
cit., but there seems to be much variation even in the specimens 
