28. AMIID^. 
93 
and very Lard, scarcely covered Ly skin. Snout short, rounded. Lat- 
eral margins of upper jaw formed by the maxillaries, which are divided 
by a longitudinal suture. Jaws nearly even in front. Cleft of the 
mouth nearly horizontal, extending beyond the small eye. Lower jaw 
broad, U -shaped, the rami well separated. Between them a broad bony 
idate, with radiating strim, its posterior edge free. Jaws each with an 
outer series of conical teeth, behind which in the lower is a band of 
rasp-like teeth. Bands of small teeth on the vomer and pterygoids. 
Palatines with a series of larger, pointed teeth. Premaxillaries not pro- 
tractile. Tongue thick, scarcely free at tip. Nostrils well separated, the 
anterior with a short barbel. Suborbital very narrow. A bony plate 
covering the cheek, similar to the plates on the top of the head. Oper- 
culum with a broad dermal border. Branchiostegals 10-12. No pseu- 
dobrauchim nor opercular gill. No spiracle. Gills 4, a slit behind the 
fourth. Gill membranes not connected, free from the isthmus. Two 
I)eculiar, long, lanceolate, obliquely striate api)eudages on each side 
of the isthmus, projecting backward and covered by the branchioste- 
gal rays, the anterior wholly aduate to the isthmus, the posterior 
free behind.* Isthmus scaleless. Gill-rakers stoutish, very short. 
Scales of moderate size, rather firm, cycloid, with a membranaceous 
border. Lateral line present. Dorsal fin long and low, nearly uniform ; 
the i)Osterior rays not much higher than the others ; its insertion in 
front of the middle line of the body, opposite the end of the pectoral. 
Tail somewhat heterocercal (more so in the young), convex behind. No 
fulcra. Anal fin short and low. Pectoral and ventral fins short and 
rounded, the ventrals nearer anal than pectorals. Vertebrm amphicoe- 
liau, as usual among fishes. Abdominal and caudal parts of the ver- 
tebral column subequal. Air-bladder cellular, bifid in front, lung-like, 
connected by a glottis with the pharynx, and capable of assisting in 
respiration. Stomach with a blind sac; no pyloric coeca. No closed 
oviduct. Intestine with a rudimentary spiral valve. Fresh waters of 
the United States. A single species known. 
* See Wilder “ On the Serrated Appendages of the Throat of Amia,” Proc. Anier. 
Assoc. Adv. Sci. 1876, 259, for a discussion of these curious organs. 
