Fig. 104.—Synaphobranchus pinnatus (Gronow). Le Have Bank.
Conger-eels.—The Leptocephalidæ, or conger-eels, are very similar to the fresh-water eels, but are without scales and with a somewhat different mouth, the dorsal beginning nearer to the head.
The principal genus is Leptocephalus, including the common conger-eel (Leptocephalus conger) of eastern America and Europe and numerous very similar species in the tropics of both continents. These fishes are strictly marine and, reaching the length of five or six feet, are much valued as food. The eggs are much larger than those of the eel and are produced in great numbers, so that the female almost bursts with their numbers. Dr. Hermes calculated that 3,300,000 were laid by one female in an aquarium.
These eggs hatch out into transparent band-like larva, with very small heads formerly known as Leptocephalus, an ancient name which is now taken for the genus of congers, having been first used for the larva of the common conger-eel. The loose watery tissues of these "ghost-fishes" grow more and more compact and they are finally transformed into young congers.
Fig. 105.—Conger-eel, Leptocephalus conger (L.). Noank, Conn.
The Murænesocidæ are large eels remarkable for their strong knife-like teeth. Murænesox savanna occurs in the West Indies and in the Mediterranean, Murænesox cinereus in Japan, and Murænesox coniceps on the west coast of Mexico, all large and fierce, with teeth like shears. The Myridæ are small and worm-like eels closely allied to the congers, having the tail surrounded by a fin, but the nostrils labial. Myrus myrus is found in the Mediterranean. Species of Eomyrus, Rhynchorhinus, and Paranguilla apparently allied to Myrus occur in the Eocene. Other related families, mostly rare or living in the deep seas, are the Ilyophidæ, Heterocongridæ, and Dysommidæ.
Fig. 106.—Larva of Conger-eel (Leptocephalus conger), called Leptocephalus morrissi. (After Eigenmann.)
The Snake-eels.—Most varied of the families of eels is the Ophichthyidæ, snake-like eels recognizable by the form of the tail, which protrudes beyond the fins. Of the many genera found in tropical waters several are remarkable for the sharply defined coloration, suggesting that of the snake. Characteristic species are Chlevastes colubrinus and Leiuranus semicinctus, two beautifully banded species of Polynesia, living in the same holes in the reefs and colored in the same fashion. Another is Callechelys melanotænia. The commonest species on the Atlantic coast is the plainly colored Ophichthus gomesi.