130 



PALAEONTOLOGY 



advance of the first anal and first dorsal. The Lipterus 

 macrolepidotus is characterized by the large size of its scales. 

 Its remains are found in the old red sandstone of many 

 localities of Scotland and England. 



In the allied genus Diplopterus the vertical fins are oppo- 

 site, but the dorsals are wider apart, and the teeth are larger 

 and fewer. Four species have been recognised in the middle 

 " old red" of Gamrie, Orkney, and Lethenbar, Boss-shire. Two 

 species occur in the carboniferous series. 



In the genus Ostcolcpis the vertical fins are alternate in 

 position, the first dorsal being near the middle of the back. 

 The teeth are sharp ; not any of the species exceed a foot in 

 length : they are all from the middle " old red." 



Family II. — Acanthodii. 



The species of this family are characterized by their very 

 small scales : they are heterocercal and notochordal. There 

 is a strong spine in front of each fin. The head is large ; the 

 orbits approximate ; the mouth wide, formed chiefly by the 

 maxillaries, and opening obliquely upwards, so that they 



Fig. 48. 

 Diplacanthus strlatus. 



have somewhat the aspect of the JJranoscopi. They have many 

 branchiostegal rays. The principal genera are from the old 



