VARIETIES OE DOMESTIC DOC.S. No one probably has ever attempted to make a complete catalogue of the varieties ofdone-lie dog: known through out the world. loft ritzinger estimated the num ber in 1870 it :111010 185. .111 these fall into cer tain groups. or type-. as will "Presently be noted: and the study of their points of likeness and un likeness has been made by several recent in•esti gators of the law of variation. One of the most recent and successful of these was a comparison by Windle of the skulls of some 60 varieties, rep resenting most of the types, the results of were extensively tabulated and discussed in the Proceedings of tlw Zoiilvgical Nociet? of London for IS90. Ile says that the most noteworthy fact learned from his comparative measurements of dog-crania was that the averages of the different breeds, especially in points relating to ,otne of the teeth. differ very little from one another; in other words, that, speaking generally, the teeth in one dog are ndatively to the skull very similar in size to those of any other. It is also to he noticed that the range of variation in any breed is much greater, in almost every case, than that existing between any two breeds. Mr. Windle says: extreme varialions in any breed are probably due to the fact that, strictly speaking, so few animals of the same group are really in any sense of the same breed. The various mem bers of a carefully selected strain of terriers, for example, tired by one breeder. might he com parable with one another, and yet quite different in descent from another and perhaps equally good strain belonging to another breeder and to another part of the country. With dogs bred for show purposes. as so many of the pure strains are, and with constantly varying requirements of fashion, all sorts of crosses, as any manual of dog-breeding will show, have been tried with a view of attaining the ideal, whether of sym metry. pace, or carriage. That such crosses should, at times at least, leave their marks upon the skulls. and cause differences in breeds which cannot be accounted for, is. of course. to be ex peeted. The presence of the disturbing factor can be appreciated, though its exact nature can not always or even frequently be ascertained with any correctness. Thus amongst the eleven bulldogs' skulls which we have examined. there was one which differed in measurements con siderably from the rest. It was nearly one cen timeter longer than any other, and, what is much more significant, it was seven centimeters longer than it was broad, the average for the others being about three or four centimeters. Moreover,
its palate was 1.90 centimeters longer than it was broad, whilst in every other ease but one the breadth exceeded the length. In the second case, the length was .90 greater than the breadth of the palate, and the length of the skull nearly five centimeters greater than the zygomatic width. We cannot doubt that both of the skulls above mentioned were those of dogs in whom, to a greater or lesser degree. there was an admix ture of strain, of what kind it is impossible to say. And what is true of these is doubtless true also lesser degree of tile greater number of specimens coining under examination. It thus becomes apparently a hopeless task to look for evidence as to the proximate or ultimate deriva tion of the breeds of domestic dogs in their skulls or Having arranged his skulls with reference to relative length and breadth, Mr. Whiffle found that the distinctly broad-headed dogs form a xvell-marked group by themselves, including the Chinese pug-nosed slianiel• the pug. bulldog. black-and tan toy terrier, and King Charles span iel, a considerable interval existing between these and the next. All these are highly artificial breeds, which require great care and attention in order to prevent deterioration, with its conse quent elongation of the skull. Next to this group conies one, la rgely consisting of terriers, with heads inclining to be broad. A miseellaneous group next follows, gradually decreasing to the distinctly narrow'-headed dogs, such as the Irish wolf-dog and the greyhound.
These investigations demonstrated the fact that in the highly artificial broad-headed dogs elom.ia tion of skull and palate is a sign of impure breeding. an evidence of admixture with the broad-headed strain of that of some other and narrower-headed dog. Examples of this may be seen almost any day in the streets in the shape of the half-bred pugs, in which the elongated !nuz zles present so great a contrast with the short, square faces of their pure-bred cousins. We have no facts before us to prove whether the long headed dogs, such as greyhounds, tend to become broader when impurely bred, but it is highly probable that they would do so, and eousequently that the dogs at both ends of the scale would, under the influence of promiscuous interbreed ing,. tend to approximate to the average head.