192 CLASSIFICATION OF FISHESj ETC. 



Cesteacion. Head not depressed ; eyes vertical ; mouth 



terminal ; lips thick ; dorsal fins spined. 

 MusTELus. AM the teeth tessellated, as in the Raids. 



3. Sub-family Zyganin^. — Head excessively dilated ; spi- 



racles large. 



Zygaxa. Head hammer-shaped. 

 Tlatysqualus. Head heart-shaped. 



4. Sub-family Crossorhin-s. — Spiracles large ; 'mouth ter- 



minal, with many cirri. 



Crossorhijtus. Dorsal fins placed near the taU. 



5. Sub-family Pristix^. — Muzzle sword-shaped, with spines. 

 Pristis. Teeth tessellated, covering the lips. 



Family 2. RAID^. Bays 

 Head and body flat ; the former more or less surrounded by 



the pectoral fins. 



Sub- family Trigonin^. — Tail armed with serrated spines. 

 Trigok. Tail with a narrow linear fin either above or below. 

 Pastixaca. Tail attenuated, and without any fins. 

 Pteroplatea. Body broader than long ; tail without fins. 

 Raia. Body prickly ; tail with small fins, but no spine. 

 Anacanthus. Resembling Trigon, but without a caudal spine. 



Sub-family Pterocephalix^. — Head detached from the 

 fins, and prominent. 



Myliobates. Tail excessively long ; head simple, without 

 appendages. 



Rhixoptera. Muzzle divided into two lobes ; mouth beneath. 

 Ceratoptera. Two fin-like processes on the muzzle ; mouth 



terminal. 

 -.^TOBATES. Lower jaw much longer than the upper. 



Pterocephala. Muzzle with fin-like processes; mouth be- 

 neath. 



Sub-family Torpedix^, — Body andpectorals'forming adisk. 

 Torpedo. With two dorsal fins. 

 Temera. Dorsal fins wanting. 



