380 MEMOIRS OF THE CARNEGIE MUSEUM. 



not produced; mandibular suspensorium nearly vertical or inclined forwards, and 

 gape of mouth wide; premaxilla very small; maxilla large, loosely attached and with 

 two well-developed supramaxillary plates; teeth small and conical. Opercular 

 apparatus complete. Vertebral centra never advanced beyond the annular stage; 

 ribs delicate; no fused nor expanded haemal arches at the base of the tail. Inter- 

 muscular bones absent. Fin-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." 

 (A. S. Woodward, I. c, Pt. Ill, p. 446-7). 



Genus Pholidophorus Agassiz. 



" Trunk not much deepened, and head relatively large. External bones smooth 

 or delicately ornamented with rugse and tuberculations ; sensory canal on suborbital 

 and preorbital plates branched; maxilla more or less arched, the oval 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 smaller than the trapezoidal operculum, 

 from which it is divided by an oblique suture; branchiostegal rays numerous. 

 Pleurocentra and hypocentra in notochordal sheath fused or separate. Fin-fulcra 

 small, extending along the foremost ray of each of the fins. Pectoral not excessively 

 large, but much exceeding the pelvic fins in size; dorsal and anal fins triangular in 

 shape, not extended, the former opposite or arising somewhat behind the pelvic 

 fins; caudal fin deeply forked. Scales thin, deeply overlapping, usually with an 

 inner rib and peg-and-socket articulation, and the external layer of ganoine smooth 

 or feebly ornamented; principal flank-scales deeper than broad, ventral scales in part 

 broader than deep; no enlarged series of ridge-scales, but a large scale at the base of 

 one or both lobes of the caudal fin, and three slightly enlarged scales round the 

 anus at the base of the anal fin. Lateral line opening by widely separated large 

 pores." (A. S. Woodward, I. c, pp. 447-8). 



The occurrence of this genus in the Lithographic Stone at Cerin was first 

 reported by ThioUiere, who recognized what he considered to be three new species, 

 without, however, describing or naming them. Wagner, in 1860, recorded the 

 presence of his newly described P. ovatus in the Cerin deposits, an identification 

 concerning which later writers appear to have entertained some doubt. The only 

 scientifically described species of this genus occurring at the Cerin locality is 

 P. similis. 



