90 CLASS IV. . ORDER VF. 
ORDER 6. CHONDROPTERYGIOUS. 
Skeleton cartilaginous, without ribs ; gill-men- 
hranes wanting, with er without gill-covers. 
Perromyzon, (lamprey,) body eel-form ; mouth 
beneath, with numerous teeth in circular rows ; 
spiracles seven on each side the neck. 
GasTrRoprancHus, (hag-fish,) body eel-form, 
mouth beneath, with numercus pectinate teeth ; 
spiracles two, beneath the abdomen. 
Rasa, (ray,) mouth situated beneath the head, 
transverse, beset with teeth ; spiracles beneath, 
five en each side ef the neck ; body, in most spe- 
cies, subrhomboidal. 
Sauays, (shark,) mouth situated beneath the 
anterior part of the head, with numerous teeth dis- 
posed in rows ; spiracles on each side the neck 
(in most species five,) of a semi-lunar shape ; body 
oblong, somewhat cylindric. , 
SpaTuLaria, habit as Squalus, ; spiracles sin- 
gle on each side the neck and concealed by a large 
gill-cover ; snout produced, spatulate ; mouth be- 
meath the head, large and furnished with sharp 
serrate teeth. , 7 
ACIPENCER, (sturgeon, sterlet,) having gill- 
covers; snout bearded beneath ; mouth beneath 
the head, ovate, toothless, retractile; body elon- 
gated, mailed above by tubercles. 
Preasus, having gill-covers; snout elonged 
not bearded ; mouth beneath ; pectoral fins large ; 
yentral fins single-rayed; body depressed, mail- 
ed, with the abdomen divided into bony segments. 
