172 
ACTIXOPTEETGn. 
II. Small scales between scutes. 
Trunk completely covered with scutes 
and small rliomboidal scales : 
dorsal fin occupying the greater 
part ol tbe back, and anal fin 
opposed to its binder portion . . Pelargorhynclius (p. 188). 
Genus DSRCBTIS 9 Agassiz. 
[Xeues Jalirb. 183-1, p. 389.] 
External bones slightly ornamented with short ridges and rows 
of tubercles. Teeth in form of small, slender, hollow cones, more 
or less clustered. Vertebrae between 50 and 60 in number. Pelvic 
fins arising nearer to the pectorals than to the anal; dorsal fin 
occupying the greater part of the back ; anal fin opposed to the 
hinder part of the dorsal ; caudal fin forked. ^lost of the dermal 
scutes considerably expanded, and the adjoining longitudinal series 
often in contact; a paired series along the dorsal and yentral 
borders, and another along the lateral line ; no intermediate 
squamation. 
Dercetis scutatus, Agassiz. 
1834. Dercetis sicutatus, L. Agassiz, Xeues Jahrb. p. 390, and Poiss. 
Foss., Feuill. p. 20. 
1844. Dercetis scutatus, L. Agassiz, Poiss. Foss. yol. ii. pt. ii. p. 259. 
Type. Xearly complete fish ; Palmontological lluseum, ILunich. 
The type species, attaining a length of about 0*35. Length of 
head with opercular apparatus equalling about one fifth of the total 
length of the fish (including caudal fin). Pectoral fins much larger 
than the peMc fins, these two pairs separated by a space about 
equal in length to the cranium ; dorsal fin, with about 50 rays, 
arising well in adyanee of the pelyic fins; anal fin, with not less 
than 16 rays, opposed to the hindermost part of the dorsal. Dermal 
scutes ornamented with fine tuberculations, and the three longi¬ 
tudinal series on each side almost or completely in contact. 
Form. Loc. Fpper Cretaceous: Eaumberg, "Westphalia. 
Xot represented in the Collection. 
The following specimens from the English Chalk probably belong 
to Dercetis.^ but are not specifically determined;— 
31075-82. Imperfect anterior portion of a large fish, comprising 
the head, clayicle, abdominal yertebree, many well- 
preserved scutes, and one of the expanded pelvic bones; 
Chalk, Grays, Essex. The cranium measures about 0*12 
