MCCULLOCH. 6 



BACK-BONED ANIMALS. Subphylum CRANIATA or VERTEBRATA. 

 LAMPREYS and HAG-FISHES. Class CYCLOSTOMATA. 

 II. Family Mobdaciidae. 



2. Mordacia Gray, Proc. Zool. Soc. 1851, p. 239 {mordax). 



2a. M. mordax. Short-headed Lamprey. Petromyson mordax Richard- 

 son, Ichtb. Erebus and Terror, 184(3. p. 62, pi. 38, 3-6 (PI. L). 

 An eel-shaped animal with a suctorial mouth armed with horny teeth by means 

 of which it rasps holes in the flesh of living fishes upon which it feeds. It is 

 marine in its younger stages, but ascends rivers to breed. Rare in New South 

 Wales. 



SHARKS, RAYS, AND GHOST SHARKS. Class ELASMOBRANCHII. 



A. Five to seven external gill-openings; dorsal spine, if 

 present not erectile; teeth numerous. 



SHARKS and RAYS. Subclass Plagiostomi (Nos. iii.-xxiv.). 

 AA. One external gill-opening; an erectile dorsal spine; teeth few. 



GHOST SHARKS. Subclass Holocephali (No. xxv. only). 



SHARKS AND RAYS. Subclass PLAGIOSTOMI. 



A. Gill-openings on the sides; pectorals not attached to the head; body subPusi- 

 form. SHARKS. Order Selachii (Nos. iii.-xvii.). 



AA. Gill-openings on the lower surface; pectorals attached to the head; body dis- 

 coid, RAYS. Order Batoidei (Nos. xviii.-xxiv.). 



SHARKS. Order SELACHII. 

 A. 6-7 gill openings; one dorsal fin. 



B. No gill-openings crossing the throat, mouth inferior. 



Family Hexanchidac (No. iii.) . 

 BB. Margin of first gill-opening free across the throat, mouth anterior. 



Family Chlamydosdachidae (No. iv.). 

 AA. 5 gill-openings; two dorsal fins. 

 C. Anal fin present. 

 D. Dorsal fins with fixed spines. Family Hetevodontidae (No. v.). 



DD. No dorsal spines. 



E. Eyes with nictitating membranes. 



F. Functional teeth upstanding, triangular, and compressed 



G. Head normally formed. Family Carchavliinidae (No. vi.). 

 GG. Head hammer or kidney shaped. 



Family Sphyi-nidae (No. viii.). 

 FF. Teeth flattened, in bands or pavements. 



Family Mustelidae (No. vii.) . 

 EE. Eyes without nictitating membranes. 



H. First dorsal over or behind the ventrals. 



I. Nasoral grooves present. Family Orectolobidae (No. ix.) . 



II. No nasoral grooves. Family Scylliorhinidae (No. x.). 

 HH. First dorsal more or less in advance of the ventrals. 



J. Caudal peduncle without lateral keels. 



K. Tail very long; more than half the total length. 



Family Alodiidae (No. xi.) • 

 KK. Tail normal; less than half the total length. 



Family Carchariidae (No. xii.j. 



