MANUAL OF NATUKAL HISTORY. 551 



Elginense of Mantell. Among the fossil fishes of 

 this epoch, we may mention the Ptychacanthus, be- 

 longing to the family of Cestracions ; genera of the 

 curious extinct family of Ccelacanthidce, with the 

 rays in the form of hollow tubes, and the tail pro- 

 duced into an elongated style. To these must be 

 added five genera of the family Cephalaspididce, 

 which have the head and front of the body covered 

 with bony plates. The Coccosteus, with an armour 

 of tuberculated bony plates, a round head and elon- 

 gated tail ; the Cephalaspis, or Buckler-head, with 

 its large head with concentric horns, and narrow- 

 jointed body ; the Holoptychius, cased in large, 

 carved scales; the Pterichtkys, or Winged-Fish, 

 with its coat of mail, strong spinous fins, and curi- 

 ous tail with the vertebrae extending as far as the 

 end ; and the Polyphractus and Pamphractus. To 

 another and equally curious family, the Dipteridce, 

 belonged the Dipterus and Diplopterus, with their 

 fins like two pairs of wings ; the Cheirolepis with 

 its scaly pectorals and small, fretted scales ; and the 

 Osteolepis, cased from head to tail in complete ar- 

 mour. To these we may add the Glyptolepis, with 

 its large, sculptured scales ; the Cheiracanthus, or 

 Thorny-hand, with spiny pectoral fins ; the Acan- 

 thodes, with a spine in each fin ; the little Dipla- 

 canthus, covered with extremely minute scales ; and 

 last, not least, the highly interesting Asterolepis, or 

 Star-scale, with its broad, plaited head, and body 

 covered with scales of solid bone, so graphically de- 

 scribed by Hugh Miller. 



