P YCNODONTIDiE. 
211 
Type. Portions of splenial dentition ; Stuttgart Museum. 
The largest species hitherto discovered, known only by the splenial 
dentition. Teeth rounded and closely arranged, smooth or feebly 
rugose, with traces of a shallow apical pit only in the lateral series. 
Teeth of principal series at least twice as broad as long, scarcely if 
at all arched, and almost equally blunt at each extremity; inner 
series very small and irregular; outer teeth in four irregular 
series, largest and broader than long or reniform in the innermost 
of these, smallest in the second and third series, which are especially 
irregular. 
Form. § Loc. Kimmeridgian : Switzerland; N. Germany k 
P. 3742. Imperfect right splenial bone, with teeth of principal and 
first outer series; Heuchatel. Enniskillen Coll. 
P. 3743. Plaster cast of a nearly similar specimen, left side; 
Soleure. Enniskillen Coll. 
28379. Imperfect right splenial dentition, of small size, doubtfully 
referable to young of this species; Soleure. The prin¬ 
cipal teeth are more arcuated than usual and nearly three 
times as broad as long ; the inner teeth are minute ; the 
second outer series of teeth is relatively larger than in 
the typical adult dentition. Purchased , 1853. 
P. 7440. Imperfect left splenial, with remains of dentary externally 
ornamented with fine tubercles ; Langenberg, Hanover. 
Purchased , 1 895. 
Mesodon affinis (Pictet). 
1860. Pycnodus ajfinis, F. J. Pictet (ex Nicolet, MS.), Kept. & Poiss. 
Foss. Jura Neuchatelois, p. 50, pis. xii., xii. bis, pi. xix. fig. 1. 
Type. Splenial dentition ; Keuchatel Museum. 
A species somewhat smaller than M. gigcis , also known only by 
the mandibular dentition, which closely resembles that of the last- 
named species, differing (1) in the relatively larger size of the 
inner series of teeth, which is sometimes duplicated, and (2) in the 
relatively smaller size and rounded form of the teeth in the inner¬ 
most of the outer series. 
Form. & Loc. Kimmeridgian : Switzerland. _ 
1 Detached teeth from the Kimmeridgian and Portlandian of Boulogne have 
also been assigned to this species by H. E. Sauvage, Catal. Poiss. Form. Second. 
Boulonnais (1867), p. 25 ; others from the Diceraskalk of Kellieim, Bavaria, by 
M. Scblosser, Paleeontogr. vol. xxviii. (1881), p. 58, pi. viii. figs. 4, 5; others 
from the Titkonian of Verona, by F. Bassani, Atti Soc. Ital. Sci. Nat. vol. xxviii. 
(1885), p. 158, pi. ii .a. figs. 10. 11. 
P 2 
