Jl LY, 1901.] 



KNOWLEDGE. 



I 51 



A far more curious modilicatiou produced by doniesti- 

 catiou is. however, displayed by the augincnWtiou in 

 tiie number of tlie horns; two, three, four, or even six 

 extra horns being sometimes noticeable. When a pair 

 of such additional horns are developed they usually 

 occupy the upper and fore part of the head, and arc of 

 a more slender shape and t^ike a more upright direction 

 than the nonnal pair, which generally retain their 

 ordinai-y position and form, although (as in the speci- 

 men here depicted) frequently showing a more or less 

 pronounced lack of symmetry. When the Zoological 

 Society possessed a farm at Kingston Hill, in the year 

 1829, several of these four-horned sheep were kept there : 

 but, although llamas and alpacas, which are just as 

 much domesticated animals, are exhibited at the present 

 day in the Society's meuagerie in the Regent's Park, 

 four-horned and other abnormal breeds of sheep 

 are not on show. Those curious in such matters may, 

 however, sec a fine four-horned ram from the Isle of 

 Mau recently presented to the British Museum by Mr. 

 G. C. Bacon, and now exhibited among the series of 

 domesticat-ed animals in course of formation in the north 

 hall. Hci-c, too, may be seen a niimber of skulls, with 

 the horns attached, of this remarkable breed; some of 

 them coming from Iceland and others from as far east 

 2s China. Five is the maximum number of horns .shown 

 in any one specimen in this collection. 



Beai-ing in mind the close aflinity existing between 

 sheep and goats, it is not a little remarkable that the 

 additional horns developed in the four-horned breed of 

 the former should approximate to a considerable degree 



FlO. 1. — Four-horned Ram, the property of Ifr. Ccimiingham, 

 of South Uist, Hebrides. 



both in direction and in cun'ature tc those of the latter. 

 This, however, must not be taken as an indication tiiat 

 I he additional pair in the four^iorned sheep represent 

 the nonnal pair of the goats. 



Some uncertainty .still exists as to whether four-horned 

 sheep belong to one or to several breeds, and also as 

 to the place of origin of such breed or breeds, although 

 they are known to be of very great antiquity. Report 

 has" it that one breed at least originally came from Ice- 

 land and the Faroe Islands, where they still exist, as 

 they also do in the Orkneys, Shetlands, Hebrides, and 

 the' Isle of Man, The four-year-old forming the subject 

 of our illustration is a Hebridcan specimen, and was 

 living in South TJist last year. Occasionally, it is said, 

 the little brown shesp of the island of Soa, in the 

 Hebrides, develop four horns, although they are nor- 

 mally two-horned. 



Like the Soa breed, Huropeaii four-horned sheep aio 

 of very small size, and dark in colour, the fleece being 

 not unficqueutly mottled with patches of brown and 

 white. The wool, too, as in most or all the inferior 

 breeds of sheep, is much mixed with hair, so that it 

 is by no means of a fine quality. 



From the islands of north-western Europe four-honicd 

 sheep may bo traced eastwards across the nurthcm 

 districts of continental Europe and Asia into China, 

 where they appear to be comparatively numerous. 

 Among the nomad Tatars, who are stated to possess con- 

 siderable llocks of these sheep, the presence of four horns 

 is associated with an enlargement of the base of the tail, 

 owing to the deposition in that region of a large amount 

 of fat. AUIunigh such a difference might be produced 

 by crossing Icelandic four-horned sheep with the two- 

 horned fat-tailed breed, it cjuite possibly indicates an 

 altogether distinct breed. IMoreovcr, Brian Hodgson, 

 a former Anglo-Indian naturalist, in a paper on the tame 

 sheep and goats of the Sub-Himalayas and Tibet, pub- 

 lished in "Vol. XVI. of the Journal of the Asiatic Society 

 of Bengal (1847), states that the Hvinia sheep of the 

 Himalaya, which are whit* with black faces, oc(!asionally 

 develop four or more horns. Again, Dai win, in his 

 " Animals under Domestication," mentions that merino 

 sheep when exported to Chili display the same tendency. 

 It would thus seem probable that there is more than one 

 breed of I'our-honiecl sheep. 



In most, if not in all, cases the two horns on each side 

 of the head in these sheep are perfectly distinct and 

 setiarate from one another at the base ; but this does 

 not prove that they may not in tho first instance have 

 originated by a splitting or division of the young horns 

 of the normal pair. 



In this connection it is very noteworthy that the 

 antlers of deer are occasionally bifuixate for a portion 

 or the whole of their length on one side of the head, 

 although there docs not seem to be an instance on I'ecord 

 where such a feature occurs on both sides. That such 

 duplicated antlers are due to a splitting during early 

 development is rendered perfectly manifest by the head 

 of a fallow-deer iigured on page 855 of the Froci'ediiKjx 

 uf the Zoological Society for 1896. In this instance it is 

 '• t,lu; right antler which is double throughout its length ; 

 ; but instead of the two divisions of this antler being com- 

 plete in every detail, the front one corresponds only 

 with the fore half of the normal complete antler, and 

 1 I'iri- vi-rsa. Hence the proof of bifurcation. 



On the other hand, in the three-horned red deer shown 

 in Fig. 2 the duplicated antlers of the right side arc 

 practically replicas of one another; both being some- 

 what simpler than the normal left antler. In this case 

 there is no evidence of bifurcation, but the three-horned 

 fallow deer seems sufficient to demonstrate that the 

 origin of the abnormality is the same in both instances. 

 If tliis bo the case, there seems no reason why the 

 additional cranial ■appendages developed in the four- 

 hovned breed of sheep should not have been originally 

 due to fission, although no trace of such original splitting 

 can now be detected. 



Splitting seems, indeed, to be a very common mode 

 by which abnormalities are produced. The museum of 

 the Royal College of Surgeons possesses, for instance, 

 the skull of a dog in which both the upper tusks, or 

 canine teeth, are longitudinally split for about half 

 their length. This splitting is dearly due to a partial 

 fission of the crown of the tooth-germ. And it is not 

 improbable that a similar fission, cai-ried to a greater 

 extent, mav explain the condition obtaining in the skull 



