Oiicida Lake Fishes 279 



PACE 



ss'. Dorsal fins two, distinct, or vcr>- slightly united. 

 2'. Anal fin with one or two spines, 

 a". Pscudobranchiae well developed. Preopcrcle serrate. Mouth large, 

 b". Mouth with many large canine teeth. A black spot at the base of the last 



dorsal spine. Size of fish large StizosledUm vilreum 441 



bb". Canine teeth absent. Body yellowish, with broad, dusky transverse bars. 



Perca fiavescens +24 

 ;ia". Pseudobranchiae very small or absent. 

 1". Prcmaxillarics protractile. Body with W-shapetl markings on the sides. 



BoUosoma nigrum olmsledi 46 ) 

 1 1 ". Premaxillarii-s not protractile. 



'1". Cranium ver>' broad between the eyes; snout conic and pig-like, project, ng 

 beyond the mouth. Sides with narrow, transverse bars or spots. .\'apc 



naked Percina atprodes zebra 437 



dtl". Cranium not bn^ad between the eyes, 

 e". Parietal n-gion of skull depressed. Vential line of belly with enlarged scales 



or with a naked strip left by their falling off HadropUrus mac uJalus 436 



ce". Parietal region of skull not depressed, but strongly convex in cross section. 

 .No modified scales or naked strip on ventral line. 

 f". Gill membrane scarcely connected. Dorsal fin VII to X — 10 to 11. 



Pcecilichlhys exiiis 463 

 fP'. Gill membranes broadly connected. Soft dorsal with 12-14 rays. 



Catonotus flabelUxris 465 

 zz'. .'Vnal fin with three spines. Body deep ami compressed. Sides silver}-, with 



several narrow, dark, longitudinal lines along the sides Lepibe ma chrysops +22 



rr'. Body without true scales and more or less armed with prickles or with a few scale-like 

 plates. Cheeks with a bony slay below eye, enduig in a spine itn the opercle. 



Collus bairdii bairdii 512 

 qr|'. Chin with a barbel; dorsal with more than 40 rays I^la maculosa 517 



E.\I'L.\.\.\TIO.\ OK TeRM.S UsKD IN THE KlLV. 



.-Uniominal ventral fins. X'cntra! fins considerably behind pectoral hns, and the 



jielvic girdle to which they are attached free from the pectoral girdle. Figs. 



180 and 181. 

 Adil<osc fin. \ rayless, commonly fleshy fin-like structure on the back, Inrhind 



the dorsal fin. Fig. 180. 

 Air bladder. .\ membranous sac filled with gas, and located ilorsally in the ImkIv 



cavity. 

 Anal fin. The nnj)aired fin on the ventral side of the fish. 

 Uarbcl. .\ii elongated, more or less thread-like apiK-ndage of the head. 

 Jiody. The Ixxly is llie region from the gill o|>enings to the anus, hut the temj 



is use«l in contiwrativc measurements to include the entire fish exclusive of 



the caudal fin. 

 Pony stay. .\ lM>ny ridge extending from the eye region liackward across the 



cheek and ending in a spine on the o|)frcle. Present in sculpins. 

 liranchiostefjal membrane. The lower or ventral part of the opercular fold, 



supiMirted by Imny rays, the branchiostegals. 

 Uramhinsteiials. Hoiiy ray> supiMirting the hranchiostegal membranes. Fig. 181. 

 lUteeal disk. .\ circular funnel-like strtuture around the mouth in lampreys. 

 Canine teeth. I'.longated, conical teeth on the jaws, iinich longer than the other 



teeth. 

 Caudal fill. The impaired fin at the posteritir end of the Ixxly ; the tail fin. 

 Caudal pedunele The narrow, jiosterior part of the IhkIv which snp|Mirts the 



catidal fin. 

 Caudal sf-nl. .\ pigment spot near the middle of the Ut^c of the camlal fin. 



