from an anatomical or a physiological point of view.  For, whilst the horn of the rhinoceros is merely a dermal production, a conglomeration of hairs cemented into one dense mass as hard as bone, and answering the purpose of a defensive weapon, besides being used for digging up the roots on which the animal lives; the horn of the ceratophora is formed of a soft, spongy substance, coated by the rostral shield, which is produced into a kind of sheath.  Although flexible, it always remains erect, owing to the elasticity of its substance.  Not having access to a living specimen, which would afford the opportunity of testing conjecture, we are left to infer from the internal structure of this horn, that it is an erectile organ which, in moments of irritation, will swell like the comb of a cock.  This opinion as to its physiological nature is confirmed by the remarkable circumstance that, like the rudimentary comb of the hen and young cocks, the female and the immature males of the ceratophora have the horn exceedingly small.  In mature females of eight inches in length (and the females appear always to be smaller than the males), the horn is only one half or one line long; while in immature males five inches in length, it is one line and a half.

[Illustration:  CERATOPHORA TENNENTII and C. STODDARTII]

Among the specimens sent from Ceylon by Dr. Kelaart, and now in the British Museum, there is one which so remarkably differs from C.  Stoddartii, that it attracted my attention, by the peculiar form of this rostral appendage.  Dr. Guenther pronounced it to be a new species; and Dr. Gray concurring in this opinion, they have done me the honour to call it Ceratophora Tennentii.  Its “horn” somewhat resembles the comb of a cock not only in its internal structure, but also in its external appearance; it is nearly six lines long by two broad, slightly compressed, soft, flexile, and extensible, and covered with a corrugated, granular skin.  It bears no resemblance to the depressed rostral hump of Lyriocephalus, and the differences of the new species from the latter lizard may be easily seen from the annexed drawing and the notes given below.[1]

[Footnote 1:  The specimen in the British Museum is apparently an adult male, ten inches long, and is, with regard to the distribution of the scales and the form of the head very similar to C.  Stoddartii.  The posterior angles of the orbit are not projecting, but there is a small tubercle behind them; and a pair of somewhat larger tubercles on the neck.  The gular sac is absent.  There are five longitudinal quadrangular, imbricate scales on each side of the throat; and the sides of the body present a nearly horizontal series of similar scales.  The scales on the median line of the back scarcely form a crest; it is, however distinct on the nape of the neck.  The scales on the belly, on the extremities, and on the tail are slightly keeled.  Tail nearly round.  This species is more uniformly coloured than C.  Stoddartii; it is greenish, darker on the sides.]