586 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiv. 
Family II. ARGENTINID^?^. 
THE SMELTS. 
Body elongate, covered with moderate or small scales, which are 
usually cycloid. Head naked. Mouth terminal, small or large, formed 
as in the Salmonidm, the maxillary forming the margin of the upper 
jaw. Teeth various, sharp-pointed. Gills 4. a slit behind the fourth. 
Gill membranes separate, free from the isthmus, with 6 to 10 branch- 
iostegals. No barbels. Stomach a blind sac, with the pyloric caeca 
few or none. Dorsal tin short, nearly median; adipose tin alwaj'^s 
present; caudal forked; anal moderate; pectorals placed low; ventrals 
moderate, nearly median; no spines in the fins. Lateral line present. 
No phosphorescent spots. Abdomen rounded. Air bladder large, 
single. Ova large, falling into the cavity of the abdomen before 
extrusion. Small fishes, marine or anadroiuous, some of them inhab- 
iting deep water; all but one genus confined to the waters of the 
Northern Hemisphere. There are about ten genera and perhaps a 
dozen species; reduced Sahnonidce, smaller and in every way feebler 
than the trout, l>ut similar to them in all respects except the form of 
the stomach. Most of them are very delicate food-fishes. 
a. Branchiostegals 6 to 10; body not cylindrical, the sides more or less compressed; gill 
membranes separate. 
h. Mouth large, with strong teeth in the jaws and on tongue, 
c. Scales large, smooth, similar in both sexes; pectoral fin moderate, its rays 
10 to 12; ventrals inserted under front of dorsal; teeth strong, those on 
tongue enlarged, c-anine-like; scales moderate, loosely attached.. 0.s/h«'ms, 6. 
}>h. Mouth rather small, with weak teeth or none; scales large, smooth; ventrals 
below middle or front of dorsal. 
d. Jaws with minute teeth; similar teeth on tongue and palate; maxillary 
reaching past front of eye Mesopm^, 7. 
(111. Jaws toothless, or very nearly so; vomer and palatines with small teeth; 
mouth very small, the maxillary not reaching past front of eye; tongue 
with a curved row of small teeth on each side; scales usually more or 
less spinescent Argentina, 8. 
6. OSMERUS (Linnaeus) Lacepede. 
SMELTS. 
Osmeris Linnaeus, Syst. Nat., lOth ed., 1758, p. 310 {eperlanus). 
Osmerus Lacepede, Hist. Nat. Poissons, V, 1803, p. 229. 
Eperlanus Gaimard, Voy. Island and Greenland. 1851 {eperlanus). 
Spirinchus Jordan and Evermaxn, Fish. N. and M. Amer., 1896, I, p. 522 
(thaleichthys) . 
Body elongate, compressed. Head long, pointed. Mouth wide, the 
slender maxillary extending to past the middle of the eye; lower jaw 
projecting; preorbital and suborbital bones narrow. Maxillaries and 
premaxillaries with fine teeth; lower jaw with small teeth, which are 
larger posteriorly; tongue with a few strong, fang-like teeth, largest 
