[Illustration:  THERAPON QUADRILINEATUS.]

In addition to marine eels, in which the Indian coasts abound, Ceylon has some true fresh-water eels, which never enter the sea.  These are known to the natives under the name of Theliya, and to naturalists by that of Mastacembelus.  They have sometimes in ichthyological systems been referred to the Scombridae and other marine families, from the circumstance that the dorsal fin anteriorly is composed of spines.  But, in addition to the general shape of the body, their affinity to the eel is attested, by their confluent fins, by the absence of ventral fins, by the structure of the mouth and its dentition, by the apparatus of the gills, which opens with an inferior slit, and above all by the formation of the skeleton itself.[1]

[Footnote 1:  See GUeNTHER’S Acanthopt.  Fishes, vol. iii. (Family Mastacembelidae).]

Their skin is covered with minute scales, coated by a slimy exudation, and the upper jaw is produced into a soft tripartite tentacle, with which they are enabled to feel for their prey in the mud.  They are very tenacious of life, and belong, without doubt, to those fishes which in Ceylon descend during the drought into the muddy soil.[1] Their flesh very much resembles that of the eel; and is highly esteemed.[2] They were first made known to European naturalists by Russell[3], who brought to Europe from the rivers round Aleppo specimens, some of which are still preserved in the collection of the British Museum.  Aleppo is the most western point of their geographical range, the group being mainly confined to the East-Indian continent and its islands.

In Ceylon only one species appears to occur, the

[Footnote 1:  See post, p. 351.]

[Footnote 2:  CUV. and VAL., Hist.  Poiss. vol. iii. p. 459.]

[Footnote 3:  Nat.  Hist.  Aleppo, 2nd edit.  Lond. 1794, vol. ii. p. 208, pl. vi.]

[Illustration:  MASTACEMBELUS ARMATUS]

Mastacembelus armatus.[1] The back is armed with from thirty-five to thirty-nine short, stout spines; there being three others before the anal fin.  The ground colour of the fish is brown, and the head has two rather irregular longitudinal black bands; deep-brown spots run along the back as well as along the dorsal and anal fins; and the sides are ornamented with irregular and reticulated brown lines.  This eel attains to the length of two feet.  The old females do not show any markings, being of a uniform brown colour.

[Footnote 1:  Macrognathus armatus, Lacep.; Mastacembelus armatus, Cuv., Val.]

In the collection of Major Skinner, before alluded to, brought together without premeditation, the naturalist will be struck by the preponderance of those genera which are adapted by nature to endure, a temporary privation of moisture; and this, taken in connection with the vicissitudes affecting the waters they inhabit, exhibits a surprising illustration of the wisdom of the Creator in adapting the organisation of his creatures to the peculiar circumstances under which they are destined to exist.