THE FISHES OF NEW JERSEY. 127 
f. Maxillary barbel minute, not quite terminal. SEMOTILUS 
ff. Maxillary barbel absent. LEUCISCUS 
ee. Postventral region tranchant, scales not passing over its edge; 
anal basis long. BRAMA 
dd. Teeth in main row 4-4, lesser row often absent. 
g. No maxillary barbels; upper jaw protractile. 
NOTROPIS 
gg. Maxillary with a small barbel near its tip. 
h. Premaxillaries not protractile; teeth 2, 4-4, 2. 
RHINICHTHYS 
hh. Premaxillaries protractile; scales 35 to 55; teeth 
4-4, or I, 4-4, I or 0, lesser row with never more 
than I. HYBOPSIS 
ec. ExocLossin#. Lower jaw singularly formed, dentary bones parallel, 
united their whole length. EXOGLOSSUM 
Genus Hypocnatuus Agassiz. 
The Gudgeons. 
Hybognathus nuchalis regius (Girard). 
(FrontispreceE—Parvt IT.) 
Gudgeon. Silvery Minnow. 
Peqde >> dept 47D, 11, 7, 1; Ad Wy 7, 12 scales 37. me 
lateral line to base of caudal, 3 more on latter; 6 scales obliquely 
back from origin of dorsal to lateral line; 4 scales between 
origin of ventral and lateral line; snout 334 in head; eye 3%; 
maxillary 4; interorbital space 214; pectoral 1; ventral 1%; 
least depth of caudal peduncle 15% ; pharyngeal teeth 4—4. Body 
elongate, somewhat compressed and slender. Head rather short, 
blunt. Snout blunt, protruding a little beyond mandible. Eye 
small. Maxillary not reaching eye. Interorbital space broad, 
convex. Gill-rakers few, short, fleshy. Scales large, uniform 
in size. Lateral line continuous, slightly decurved. Intestines 
long, more than 7 times length of body. Peritoneum black. 
Dorsal inserted nearer tip of snout than base of caudal. Anal 
inserted behind tip of depressed dorsal. Caudal deeply forked, 
lobes pointed. Pectoral about 34 of space to ventral. Ventral 
inserted behind origin of dorsal and reaching about °/, of space 
to anal. Color mostly silvery, back pale translucent olive. Fins 
pale, dorsal and caudal a trifle dusted. Iris silvery. Length 
4% inches. Trenton. 
