PISHES. 213 



ff Scales ganoid, diamond-shaped, enamelled plates; snout 



lengthened, depressed. . . Rhomboganoidbi, DD. 



** Skeleton chiefly cartilaginous ; body naked or with 3 to 5 rows 



of bony bucklers ; vertical flns with fulcra. (Chondrogan- 



OIDEI.) 



J Mouth terminal, broad; lower jaw, maxillaries and palate 



with many minute, deciduous teeth. Sblachostomi, EE. 



jfi Mouth narrow, inferior, toothless. . Chondrostbi, FP. 



CC. FAMILIES OF CYCLOGANOIDEI. 



* A broad bony plate between branches of lower jaw; vertical 



flns without fulcra; dorsal fin very long of more than 40 

 rays ; body stout Amiidub, 113. 



DD. FAMILIES OF RHOMBOGANOIDEI. 



* Vertical fins with fulcra; dorsal short, far back, of less than 12 



rays ; body elongated. . . . LbpidostbidjB, 113. 



EE. FAMILIES OF SELACHOSTOMI. 



* Skin naked ; snout produced into a flat blade ; opercle with a 



long- flap POLYODONTID^, 114. 



FF. FAMILIES OF CHONDROSTEI. 



* Body with 5 rows of bony shields (rarely deciduous) ; snout 



produced ; four barbels in front of mouth. 



ACIPBNSEKnXS!, 115. 



