196 DESCRIPTION OF FISHES. 
also found a few examples of a much rarer family of cartilaginous fishes, called 
Chimeroids ; the Bracklesham fossils of this family belong to the extinct genera 
Edaphodon and Elasmodus. 
The fossil remains of the osseous order of fishes are few in number, and 
belong to the families Si/uride and Sphyremde, and to the genus Platylemus. 
The Squalide or Sharks have usually teeth conical and sharp-pointed, with a 
more or less compressed form, sometimes with trenchant or serrate edges and 
accessory basal denticles. 
The Raiide or Rays found in that locality have teeth more compact than the 
Squalide, forming a kind of mosaic pavement in both upper and lower jaws. 
Professor Owen observes in his ‘ Odontography,’ page 47, speaking of the 
Myliobates which belong to the family Raiide, ‘‘ that the jaws which support 
and work their dense and heavy teeth, are proportionally strong, and in Ato- 
bates they nearly approach the density of true bone ; in this subgenus the upper 
jaw is shorter and more curved than the lower, the anterior extremity of which 
projects beyond the upper jaw, and can be used like a spade in digging out shell- 
fish, &c. ;”’ and page 48, ‘‘ the teeth of the Myliobates, like those of the rest of 
the Plagiostomes, are successively formed at the posterior part of the tesselated 
series, in proportion as they are worn away in front.” This worn and rugged 
character is well preserved in fossil specimens. 
One or two specimens of an existing species of this curious genus, Myliobates 
Aquila (Eagle Ray), have been taken, according to Mr. Yarrell, on the English 
coast ; they abound in the Mediterranean and Southern seas. The jaws and teeth 
of the Zygobates, one of this family, are often brought from China in the boxes 
containing crustacea and insects. Few fossils perhaps would have more per- 
plexed a comparative anatomist than the palatal tooth of an extinct Myliobates, 
unless he had been acquainted with the recent genus. 
The chimeroid genus Edaphodon, discovered and so named by the Very Rev. 
Dr. Buckland, had teeth adapted for crushing and bruising enclosed in the sub- 
stance of the jaw, which are easily perceived by their peculiar structure. In the 
Edaphodon they are three in number, arranged in a horizontal position, their 
superior surfaces being more or less worn down and pitted, showing the remains 
of calcigerous tubes. 
The Pristis or Saw-fish.—This curious fish has derived its name from a very 
singular and formidable weapon projecting from the anterior part of the head, 
provided with strong teeth as they are called, situated in a series of deep alveoli 
