PH0L1D0PH0KIDJ2. 
447 
beyond the annular, stage; ribs delicate; no fused or expanded 
haemal arches at the base of the tail. Intermuscular bones absent. 
Pin-fulcra present, but usually small; dorsal and anal fins small, 
the former above or behind the pelvic fins. Scales ganoid, more or 
less rhombic, but deeply overlapping, and the hinder margin often 
somewhat rounded. 
Synopsis of Genera. 
I. Flank-scales united by peg-and-socket, not 
excessively deepened. 
Pectoral and pelvic fins small; dorsal in 
advance of anal. 
Pectoral fins greatly enlarged, and pelvic fins 
small; dorsal opposed to anal . 
II. Flank-scales united by peg-and-socket, one 
series excessively deepened. 
Pelvic fins absent; dorsal opposed to anal; 
ventral scales broader than deep; lateral 
line along deepened scales. 
Pelvic fins small; dorsal in advance of anal; 
ventral scales as broad as deep ; lateral 
line along deepened scales.. 
Pelvic fins small; dorsal opposed to anal; 
ventral scales about as broad as deep ; 
lateral line deflected to upper series of 
ventral scales . 
III. Flank-scales not united by peg-and-socket, 
not excessively deepened. 
Pectoral and pelvic fins of moderate size ; 
dorsal and anal opposed; scales thin . . 
IV. Flank-scales imknown. 
Fins with long slender fulcra, and dorsal in 
advance of anal ; large caudal ridge- 
scales . 
Pholidophorus (p. 447). 
Thoracopterus (p. 478). 
Pholiclopleurus (p. 479). 
Peltopleurus (p. 481). 
Pleuropholis (p. 482). 
Arcliceomcene (p. 488). 
Ceramurus (p. 489). 
Genus PMOLIDOPMOH-US; Agassiz. 
[Neues Jahrb. 1832, p. 145.] 
Syn. (P) Microps, L. Agassiz, Poiss. Foss. vol. ii. pt. i. 1833, p. 10. 
Trunk not much deepened, and head relatively large. External 
bones^ smooth or delicately ornamented with rugae and tubercula- 
tions ; senSbty canal on suborbital and preorbital plates branched ; 
maxilla more or less arched, the oral margin convex and provided 
with minute teeth ; mandibular teeth larger, but still minute and 
arranged in a single series. Preoperculum broad mesially and 
marked with slight radiating furrows; suboperculum large, but 
