350 
ACTINOPIEPvYGII. 
the total length to the base of the caudal fin. Pectoral fins long 
and narrow ; pelvic fins approximately midway between the pectoral 
and caudal fins ; space between occiput and origin of dorsal fin 
about equal to length of cranium; anal fin probably with about 12 
rays. 
Form. ^ Log. Neocomian : Yoirons, Switzerland; Hanover. 
P. 8339. Imperfect fish, 0-21 in length, exhibiting general pro¬ 
portions and most of its essential characters; “Hilsthon,” 
Hildesheim, Hanover. The mouth is shown, and the 
great extent of the dorsal fin is indicated by fragments. 
The course of the simple lateral line is traceable low on 
the flank of the anterior abdominal region. 
Presented hy Prof. A. von Koenen, 1897. 
P. 7184 a. Somewhat larger head and abdominal region; “Hilsthon,” 
Hildesheim. The contours of the displaced premaxilla 
and mandible are distinct. The preoperculum is con¬ 
siderably expanded at the angle and is shown to have 
been marked with delicate radiating grooves. The origin 
of the dorsal fin is indicated by remains of a few spinous 
rays. The course of the lateral line, low on the flank 
aud gradually rising behind, is conspicuous. 
^ ^ ‘ y ' Purchased, 1894. 
P. 8640-43. Three small imperfect specimens, of which two are in 
counterpart, also a detached tail as large as that of the 
t 3 ’pe specimen; “ Hilsthon,” Hildesheim. No. P.8642 
shows the extent of the dorsal and anal fins, but both are 
too imperfect for precise description. The anal fin is in 
great j^art opposed to the hinder portion of the dorsal. 
Presented hy Prof. A. von Koenen, 1897. 
P. 7184-85. T wo small imperfect specimens, the first showing the 
small, slender, mandibular teeth, and also an impression 
of the characteristic, expanded preoperculum displaced 
above the head; “ Hilsthon,” Hildesheim. 
Purchased, 1894. 
ftp iyjpA Genus SYLIiklMUS, Cope. 
[Vert. Cret. Perm. West (Kep. U.S. Geol. Surv. Territ. vol. ii. 
1875), p. 180.] 
Apparently differing from Crossognathus only in the still more 
remote position of the pelvic fins and the absence of an anal fin. 
