Jordan and Evcrmann. Fishes of North America. 2033 



ff. A long barbel at tap of chin; snout long (produced into form of a tube, 

 as in Syngnathidce) ; body subterete, very slender, its plates not 

 spinous. PALLASINA, 765. 



bb. Gill membranes joined to isthmus, with or without a narrow free fold behind. 



j. Tip of snout without free median plate or spine; mouth inferior, lower jaw 



short. 

 k. Vomer without teeth, 



Z. Lower side of snout with no barbels; one pair of spines on tip of 

 snout. LEPTAGONUS, 766. 



II. Lower side of snout with barbels. 



'in. Gill membranes without barbels; a pair of complex barbels 

 under tip of snout ; 1 pair horizontal and 1 pair recurved 

 spines at tip of snout. Lower jaw very weak; teeth feeble, 

 sometimes wanting ; plates of body mostly with spines. 



PODOTHECUS, 767. 

 mm. Gill membranes with scattered barbels. 



n. Plates of body without prominent spines ; no preocular 



spines. AGONUS, 768. 



nn. Plates of body largely spinous; a pair of preocular 



spines. STELGIS, 769. 



kk. Vomer and, often, palatines with teeth. 



o. Dorsal fins rather long, the rays shortened behind, the last one 

 attached by membrane to the body ; no large life-like spine above 

 eye. 



p. Plates on body largely spinous ; gill membranes with cirri, 1 



or more on each branchiostegal ; teeth on palatines ; lower 



jaw short beneath the long snout.* AVERRUNCUS, 770. 



pp. Plates on body largely unarmed; no teeth on palatines; gill 



membranes without cirri. SARRITOR, 771. 



oo. Dorsal fins rather short, the rays scarcely shortened behind, the 



last one not adnate by membrane behind ; a large knife-like spine 



over each eye ; plates on body largely spinous ; no cirri on gill 



membranes. XYSTES, 772. 



jj. Tip of snout with a free terminal plate or spine; teeth on jaws, vomer, and 



palatines. 

 q. Occiput without distinct pit; 2 pairs of occipital spines; dorsal and anal 



well developed. 



r. Lower jaw strongly projecting; lower pectoral rays not much pro- 

 duced ; terminal rostral plate with 3 spines. BATHYAGONUS, 773. 

 rr. Lower jaw not projecting; lower rays of pectorals much produced 

 in adults; anal fin short, of 6 or 8 rays. XENOCHIRUS, 774. 



qq. Occiput with a deep pit; occipital spines none, or reduced to mere 



traces ; dorsal and anal very short. 



*. Body slender, elongate; tail not compressed. ODONTOPYXIS, 775- 

 8S. Body short and broad in front; tail compressed teeth. 



BOTHRAGONUS, 776. 

 ASPIDOPHOROIDIN^E : 



act. Spinous dorsal absent ; body not compressed, its plates not spinous ; mouth small, 

 terminal ; gill membranes free from the isthmus. ASPIDOPHOROIDES, 777. 



759. PERCIS,t Scopoli. 



Percis, SCOPOLI, Int. Hist. Nat., 454, 1777 (japonicus). 



Hippocephalus, SWAINSON, Nat. Hist. Fishes, etc., n, 272, 1839 (superciliosus). 



* Jaws subequal in Ayonopsis, a South American genus very close to Averruncus. 

 t Dr. Gill has called our attention to the identity of Percis with Hippocephalus. 



