Mackopteuous Abdominals.- 
-I'lSHES.- 
-Ajiidans. 
151 
are handsome small fishes, of comparatively little eco- 
nomic value. 
The genera are — Osteoglossmn; Ischnosoma; and ITyodon; 
such species as inhabit the waters of the United States being 
called Gold-eyes, Toothed Herrings, Moon-eyed Herrings, and 
Shiners. 
Family XIV.— ERYTHRINOIDS {Erythrinidce). 
This small group, named Erythroidcs by Valen- 
ciennes, contains some genera whose true affinities 
have not yet been ascertained by ichthyologists. The 
Erythrinoids have moderately thick bodies, with rounded 
backs and bellies. The upper arch of the mouth is 
formed by the premaxillaries, and the maxillaries, arti- 
culated to their extremities, are both, together with 
the mandible, crowded with small conical teeth. Tire 
vomerine mesial line is smooth, but on each side of it 
an arched plate of villiform teeth lines the vault of the 
mouth. The entire cheek is covered by bony sub- 
orbitar scales, followed by two temiwral plates which 
are characteristic of the family. The stomach is coni- 
cal and siphonal, and the pancreatic creca are numerous. 
The ovisacs do not communicate with the cavity of 
the belly, and the air-bladder is double ; the roundish 
anterior chamber being clothed with a thick, exterior, 
loosely-adhering capsule, which is inserted into the 
processes of the third and fourth vertebrre, but does 
not communicate with the labyrinth of the ear ; the 
second chamber is cellular anteriorly, without exten- 
sive partitions, but with recesses formed by longitudinal 
and transverse bridles and folds of the interior coat. 
A pneumatic tube leads from the second chamber to 
the top of the oesophagus. They are Characini with- 
out adipose fins. 
The genera are — Erythrinus ; Macrodon ; Lehiasina ; Pyrr- 
Imlina; Umhra; Melanura (Agassiz); Dusswniera; and 
Etrumeus. 
Of these Umbra and Macrodon want cells in their 
simple air-bladder. Valenciennes remarks that Ery- 
thrinus agrees with the Salmonoids in the structure 
of the face ; with the Cyprinoids in the size of the 
lateral occipital openings ; with the Clupeoids in the 
parieto-occipital foramina, and in the form of the 
basilar occipito-sphenoid bone ; with the Cyprinoids 
again in the confiuence of the anterior vertebrre, and 
in the existence of a chain of ossicles connected with 
the first chamber of the air-bladder, but not reaching 
to the vestibule of the ear, as in the Cyprinoids. Most 
of the family inhabit tropical or subtropical countries. 
Erythrinus cinereus is the “ Waubeen” of Trinidad. 
The Macrodons bear the native names of Tareira, 
Guavina, and H'dimara in South America ; and one 
species {Macrodon ferox) is called Yarrow in the island 
of Trinidad (Gill) ; Umbra is the Hundjisch of the 
Austrians. 
Family XV.— ELOPIANS {Elopidoe). 
This family group is distinguished from others by 
the presence of a sublingual bone between the limbs 
of the mandible and behind the branchiostegal mem- 
brane ; also by an unusual number of branchiostegals. 
The mouth is like that of the Clupeoids, bordered 
above by small premaxillaries, and flanked by long, 
free maxillaries. Teeth exist on all the dentiferous 
bones, but so fine as to appear merely a roughness. 
Body long and rounded, without serratures on the 
belly. Dorsal fin situated in the middle of the length. 
At the base of the deeply-forked caudal, above and 
below, there is a large indurated scale ; and long scaly 
appendages are seated in the axillm of the pectorals 
and ventrals. The head is naked, and the eyes fur- 
nished with a waxy-looking membrane. Stomach 
conical; numerous pyloric cseca ; air-bladder large, 
forked anteriorly, and communicating with the diges- 
tive caudal, but not entering the cranium. 
The genera are — Elops and Megalops. 
These fish have a variety of local names in the 
United States and West Indies, such as Silver- 
fish, Round-fish, Herrings, Pounders, Pond King-fish, 
Cafl’um, Lisa-francesa, Banana, Caballero, Saballo, and 
Savale. In the Red Sea they are termed Machnat ; 
in Hindostan, Inagore ; and in China, Chuh-Keaou. 
They attain a considerable size, and most of the spe- 
cies, though sea-fish, thrive in fresh-water ponds, 
where they fatten on the guts of fowls and other gar- 
bage thrown to them. 
Family XVI.— AMID ANS {Amioedee). 
The Mud-fish of the United States have attracted 
much attention from ichthyologists on account of the 
structure of their air-bladders, and M. Valenciennes 
remarks that the single genus Amia of ten or twelve 
species constitutes of itself a small family of fishes. 
The air-bladder is very large, enveloping the oesophagus 
and stomach, and communicating with the digestive 
canal near the pharynx. It is forked anteriorly, and 
its horns, as well as its lateral and superior parts, are 
divided into numerous cells, which expand towards 
their bottoms, forming bags. This congeries of cells is 
provided with a dense net-work of delicate bloodvessels, 
and is therefore believed to act a part in the oxygena- 
tion of the blood. The pneumatic tube is very short, 
but at the same time very wide, and issuing from near 
the anterior fork of the air-bladder, enters the oesopha- 
gus by an oblong cleft which has two tumid lips like 
those of a glottis. Another characteristic of the Ami- 
dans, is a sublingual bone like that of the Elopians. 
The naked cranium, supratemporals, snborbitars, and 
operculum are sculptured, but the interior of the mouth 
is like that of a trout, except that there are no lingual 
teeth. The ova drop into the cavity of the abdomen 
like those of a salmon. The caudal comes farther for- 
ward above than below. 
These fish can live for some length of time out of 
water, and travel from one piece of water to another. 
They have a spiral valve in the crecum, but otherwise 
resemble tbe Cyprinoids in the simplicity of the intes- 
tinal canal without cseca. They have been considered 
to be Ganoids, but the latest observations are against 
such an arrangement. 
