Only family, Coeciliidae. About forty species are known. These have been placed in seventeen genera, mostly on comparatively slight grounds, and several of these genera are probably unnatural, the distinctive characters having undoubtedly been developed independently in various countries. We have to remember that the recent species are the remainder of a formerly much more numerous group; it is also likely that more will be discovered in the tropical forests of South America and Sumatra.
Boulenger[[42]] has distinguished them as follows:–
I. Cycloid scales embedded in the skin.
A. Eyes distinct, or concealed under the skin.
a. Two series of teeth in the lower jaw.
α. Quadrato-jugal (squamosal) and parietal bones in contact.
Tentacle between eye and nostril.
Ichthyophis, 2 species, India and Malay islands, p. [90].
Tent"cle below and behind nostril.
Hypogeophis, 3 species, East Africa and Seychelles, p. [92].