1018 Bulletin ^7, United States National Museum. 



places them in 8 genera. We are unable, however, to stop with that 

 number of divisions. If they are not all placed in one genus each struc- 

 tural type must stand as a genus by itself. {Perclda', part, Giinther, Cat., 

 1,58-78, 1859.) 



/. Pseudobranchite well developed; preopercle serrate, the teeth on its lower margin autrorse; 

 branchiostegals 7; no anal papilla; premaxillaries protractik'; skull not especially cav- 

 ernous; mouth large, terminal. 



LUCIOPEUCIN.'E ; 



<i. Canine teeth on jaws and palatines; body elongate. 



h. Ventral fins well separated, the distance between them equal to the width of their 

 base; spines of second dorsal and anal very feeble, closely appressed to the soft 

 rays; dorsal fins well separated; canines strong. Stizostedion, 463. 



Percin'.?;: 



((«. Canine teeth none; body oblong; ventral fins near together; mouth large. Perca, 464. 

 IL Etheostomin.t:: 

 Pseudobranchire imperfect or wanting; preopercle entire or nearly so; branchiostegals 6; anal 

 papilla usually present; pyloric cteca 2 to 6; supraoccipital crest low or wanting; fishes of 

 small size, all American. 



c. Parietal region of skull rather depressed, not .strongly convex in transverse section, 

 ■- — ^-shaped in section; bones of skeletonratherslender and thin; vertebrae 38 to 44. 

 d. Cranium broad between the eyes; premaxillaries not protractile; snout conic, pig- 

 like, projecting beyond the inferior mouth; veutrals separated by an interspace 

 equal to the width of their base; ventral line with a series of enlarged scales 

 which fall leaving a naked strip; dorsal spines numerous (13 to 15); gill mem- 

 branes separate; scales small; vertebra: 23 + 21 = 44; size largest of the darters. 



Percina, 465. 

 dd. Cranium not broad between the eyes; mouth less inferior, the snout not much 

 projecting, 

 e. Body not hyaline nor extremely elongate, its surface almost entirely covered 

 by scales. 

 '■. Premaxillaries not protractile, free only at the sides, the skin of the pre- 

 maxillaries in front, firmly connected mesially witli that of the fore- 

 head, with no cross groove between; anal fin always large, rarely 

 smaller than second dorsal. 



1. Seven (exceptionally 8) branchiostegals; maxillary large, exposed, free behind; 



premaxillaries protractile; preopercle serrated. 

 No canine teeth; ventrals close together. 1. Perca. 



More or less enlarged canine teeth; ventrals separated by an interspace at least equal 

 to % the width of their base. 2. Luciopkrca. 



2. Six branchiostegals; maxillary small, its upper border if free, entirely or nearly 



entirely slipped under the preorbital. 

 a. Maxillary free from preorbital. 



a. Premaxillaries free only at the sides. 

 Ventrals separated by an interspace equal to the width of their b.ase. 3. Percina. 

 Veutrals separated by an interspace considerably less than the width of their base. 



4. Etiieostoma. 

 p. Premaxillaries protractile, entirely free from the skin of the snout. 



Ventrals separated by an an interspace nearly equal to the width of 

 their base. 



5. BnLKil.^OMA. 



Ventrals narrowly separated. 6. I'i.hcentka. 



b. Maxillary adnate to preorbital; ventrals narrowly separated. 7. Diplesium. 

 B. Body cylindrical or somewhat depressed. 



a. Maxillary exposed, its upper border slipping under the preorbital; body translucent. 

 Premaxillaries protractile. 8. Ammockypta. 



Premaxillaries free only at the sides. 9. Crystallauia. 



b. Maxillary covered by preorbital; premaxillaries free only at the sides. 



10. AspRO. 

 rr. Head with very largo muciferous cavities above and on the sides. 



Two dorsals; maxillary exposed, free behind. 11. Percahina. 



Dorsals united; maxillary covered by preorbital. 12. Aceeina. 



