species existing nasal found rhinoceros horn horns
MAINIMALIA, VOI. XV. p. 428).
The following are the general characters applicable to all the members of the family.
First, as regards dentition. Incisors variable, generally reduced in number and often quite rudimentary, and early deciduous. Canines, in existing species, absent. Molar series, consisting of the full number of four premolars and three molars above and below, all in contact and closely resembling each other, except the first, which is much smaller than the rest and often deciduous. The others gradually increasing in size up to the penultimate. The upper molars have a very characteristic pattern of crown, having a much-developed flat or more or less sinuous outer wall, and two transverse ridges running obliquely inwards and backwards from it, terminating internally in conical eminences or columns, and enclosing a deep (middle) sinus between. The posterior sinus is formed behind the posterior transverse ridge, and is bounded externally by a backward continuation of the outer wall and behind by the cingulum. The anterior sinus is formed in the same manner, but is much smaller. The middle sinus is often intersected by vertical laminm (" combing plates.") projecting into it froin the anterior sur-face of the posterior transverse ridge or from the wall, the development of which is a useful guide in discriminating the species, especially those no longer existing and known only by the teeth and bones. The depressions between the ridges are not filled up with cernentum as in the horse. The lower molars have the crown formed by a pair of crescents ; the last has no third lobe or talon.
It results from this that the horn has the appearance of a mass of twglutinated hairs, which, in the newly growing part at the base, readily fray out on destruction of the softer intermediate substance ; but the fibres differ from true hairs in growing from a free papilla of the derm, and not within a follicular involution of the same.
The Rhinoceroticlw are all animals of large size, but of little intelligence, generally timid in disposition, though ferocious when attacked and brought to bay, using the nasal horns as weapons, by which they strike and toss their assailant. Their sight is dull, but their hearinff and scent are remarkably acute. They feed on herbage, slTrubs, and leaves of trees, and, like so many other large' animals which inhabit hot countries, sleep the greater part of the day, being most active in the cool of the evening or even during the night. They are fond of bathing and wallowing in water or mud. None of the species have been domesti-cated. Animals of the group have existed in both the Old and New Worlds since the beginning of the Miocene period. In America they all became extinct before the end of the Pliocene period. In the Old World their distribution has become greatly restricted, being no longer found in Europe and North Asia, but only in Africa and in portions of the Indian and Indo-Malayan regions.
The existing species of rhinoceros are naturally grouped into three sections, which some zoologists consider of generic value.
I. Rhinoceros proper. The adults with a single large compressed incisor above on each side, and occasionally a small lateral one ; below, a very small median, and a very large, procumbent, pointed lateral incisor. Nasal bones pointed in front. A single nasal horn. Skin very thick, and raised into strong, definitely arranged ridges or folds.
There are two well-marked species of one-horned rhino-ceroses. (1) The Indian Rhinoceros, R. unicornis of Lin-nmus,1 the largest and best known, from being the most frequently exhibited alive in England, is at present only Roman shows, was of this species. It was sent from India to Emmanuel, king of Portugal, in 1513 ; and from a sketch of it, taken in Lisbon, Albert Diirer composed his cele-brated but rather fanciful engraving, which was repro-duced in so many old books on natural history. (2) The Javan Rhinoceros, R. sondaicus, Cuvier, is distinguished by smaller size, special characters of the teeth and skull, and different arrangement of the plications of the skin (as seen in the figures) ; the horn in the female appears to be very little developed, if not altogether absent. This has a more extensive geographical range, being found in the Bengal Sunderbans near Calcutta, Burmah, the Malay Peninsula, Java, Sumatra, and probably Borneo.
Ceratorhinus. The adults with a moderate-sized compressed incisor above, and a laterally placed, pointed, procumbent incisor below, which is sometimes lost in old animals. Nasal bones narrow and pointed anteriorly. A well-developed nasal, and a small frontal horn separated by an interval. The skin thrown into folds, but these not 80 strongly marked as in the former section. The smallest living member of the family, the Sumatran Rhinbceros, R. sumatrensis, Cuv., belongs to this group. Its geo-graphical range is nearly the same as that of the Javan species, though not extending into Bengal ; but it has been found in Assam, Chittagong, Burmah, the Malay Peninsula, Sumatra, and Borneo. It is possible that more than one species have been confounded under this designation, as two animals now living in the London Zoological Gardens present considerable differences of form and colour. One of them, from Chittagong, has been named by Sclater R. lasiotis, the Hairy-Eared Rhinoceros, but until an opportunity is afforded for anatomical ex-amination, it is difficult to pronounce upon the value of the distinction.
Atelodus. In the adults, the incisors are quite rudi-mentary or entirely wanting. Nasal bones thick, rounded and truncated in front. Well-developed anterior and pos-terior horns in close contact. Skin without any defiuite permanent folds.
The two well-marked existing species are peculiar to the African continent.
the inroads of - European civilization, and especially of English sportsmen. It feeds exclusively upon leaves and branches of bushes and small trees, and chiefly frequents the sides of wood-clad rugged hills. Specimens in which the posterior horn has attained a length as great as or greater than the anterior have been sepapated under the name of R. keitloa, but the characters of these appendages are too variable to found specific distinctions upon. The two-horned African rhinoceros is far more rarely seen in mena-geries in Europe than either of the three Indian species, but one has lived in the gardens of the London Zoological Society since 1868. Excellent figures from life of this and the other species are published in the ninth volume of the Transactions of the society, from which the accompanying woodcuts are reduced.
Extinct Species of 1?hinoceros. - The family once contained many more species, which were far more widely distributed than at present. As in similar cases, our knowledge of them is as yet but fragmentary, though constantly augmenting, especially by dis-coveries niade in the Tertiary deposits of North America, a region in which they all died out long ago, though, judging from the evidence at present available, this was the locality in which they first made their appearance. In the Eocene formations of the Rocky Mountains are found the remains of numerous modifications of the primitive Perissodaetyle type, from which the rhinoceroses may have originated. In the Lower Miocene a form called Ifyracodm by Leidy already presented many of the chaeracteristics of the family, though, especially as regards the dentition, in a. very generalized condition. The next stage of specialization is represented by Aceratherium. found in the Mioc,ene of both Europe and America, which still, like the last, shows no sign of having possessed a nasal horn. It differed from the existing species also in having four toes on the anterior limb, instead of only three. At the same period forms occurred (Dicera-therium, Marsh) which show a pair of lateral tubercles on the nasal bones, apparently supporting horns side by side. These, how-ever, soon disappeared and gave way in the Ohl World to species with one or two horns in the median line, a stage of development which apparently was never reached in America. In the Pliocene and Pleistocene of Europe and Asia numerous modifications of the existing types have been found. The present African two-horned type was represented in the Early Pliocene of Greece by B. pachy-gnathms, the skeleton of which is described by Gaudry as intermediate between the existing R. bieornis and R. simus. As many as three species were inhabitants of the British Isles, of which the best known is the Tichorhine or Woolly Rhinoceros, R. antiquitatis of Blumenbach, nearly whole carcases of which, with the thick woolly external covering, have been discovered associated with those of the mammoth, preserved in the frozen soil of the north of Siberia, and which, in common with some other extinct species, had a solid median wall of bone supporting the nasals, from which it is in-ferred that the horns were of a size and weight surpassing that of the modern species. The one-horned Indian type was well repre-sented under several modifications (E. sivalensis, paleeindicus, &c.), in the Pliocene deposits of the sub-Himalayan region, and forms more allied to the African bicorn species have also been found in India. R. schleirmacheri of the late European Miocenes was in some respects allied to the existing Sumatran rhinoceros, possessing incisor teeth and two horns. (W. H. F.)