138 ARTHRODIRAN LUNG-FISHES 
but its pectoral appendages as well. The size of the 
pectoral girdle is, of course, little proof that an anterior 
pair of fins must have existed, since this may well have _ 
been evolved in relation to the muscular supports of 
plastron, carapace, trunk, and head. The inter-movement 
of the dental plates, seen especially in Dinichthys, is a 
further difficulty in accepting their direct descent from 
the Dipnoans. | 
