A. G. Ruthven

The Faunal Affinities of the Prairie Region of Central North America

THOSE who are acquainted with the literature of the field zoology of North America are familiar with the fact, that, from the tiume of the Pacific Railroad surveys, naturalists have noted that there are in North America several well-defined biological regions. These have been pointed out at various times by Allen, Cope, Merriam and others, and the fauna. of each has been more or less investigated. Of late years there has been a teiidency among biologists to discredit this kind of work, owing to the apparent tendency of some naturalists to consider the mapping of these regions as an end in itself, but it seems to me that this work, if done properly, has a very real value. If it is true that the formation of species among verte1)rates is orthogenetic, as Whitman (1907) holds for pigeons, and I have found to be true in the garter-snakes (Rutlhven, 1908), and these species are associated with different sets of environmental conditions, as seems to be the case, for example, in the genera Leptinotarsa (Tower, 1906) and Thamnophis (Ruthven, 1908), it is manifestly of importance that these areas of characterization be determined. Certain it is that the areas of characterization will not be the same for all animals, for the reaction of any form to any set of environmental conditions depends fundamentally upon the constitution of the animal, and this is a variable. On the other hand, in the case of terrestrial vertebrates, there would seem to be enough similarity in their mode of life to render

A Contribution to the Theory of Orthogenesis

SEVERAL reasons have been given why biological discussion has, for a number of years, ceased to center about the fact of evolution and is now chiefly concerned with the factors, for such is evidently the case: the principal aim of modern biological researches is apparently to throw light upon the question of method. It is now a. part of comnmon knowledge that Darwin considered the natural selection of fluctuating variations to be the principal factor in evolution, and some of his successors have gone so far as to see in it a sufficient one; but, while few biologists will probably be disposed to deny that natural selection is an efficient factor in evolution, there seems to be now on hand a sufficient. body of data to show that it is far from being the only one. Among other methods2 that have been emphasized, mutation and orthogenesis may be mentioned, each of which has its adherents, and it is the last named of these that seems to be the principal one concerned in the evolution of a group of snakes that I have recently monographedthe genus Thamnophis (the garter-snakes) .3 I will briefly summniarize the conditions that prevail in this group: 1. The genus Thamnophis consists of four groups of

A Preliminary Note on the Variation of Scutellation in the Garter Snakes

A Preliminary Note on the Variation of Scutellation in the Garter Snakes.Three years ago the writer began an investigation into the relationships of the different races of garter snakes (Thannophis) in an attempt to determine the laws involved in the differentiation of the genus. The results of this work are being included in a monograph of the genus, but as it will be several months before this work can be completed it has been thought best to publish a brief outline of some of the conclusions. In the progress of this investigation it was seen very early that before a serious attempt could be made to determine the affinities of the different races, the significance of the variations in scale arrangement or scutellation must be determined. This was attempted with the following results: (1) The number of dorsal scale rows on an individual snake decreases posteriorly by the elimination of certain rows, and the series eliminated are always the same for snakes with the same number of rowjs, as for example T. sirtalis and T. satrita. (2) The rows dropped posteriorly in individual snakes are those which have entirely disappeared in races with a fewer number of scale rows. (3) The reduction in the number of dorsal scale rows is generally accompanied by a reduction in the number of labial, ventral, and subcauclal scales (gastrosteges and urosteges). (4) There is considerable evidence that the reduction in scutellation is directly or indirectly associated with a diminution in size. The general reduction in scutellation described above is exhibited by each of the several (natural ?) groups into which the genus can be divided. These groups all occur together only in northern Mexico, which may be considered the center of origin for the genus. The races that occur in this region all exhibit the maximum scutellation for their respective groups, the dwarfing in size and scutellation taking place at points away from the center of origin. The cliscovery of these methods of variation in the different series of scales has been an indispensable aid in determining the affinities of the clifferent races. ALEXANDER G. RUTHVEN

BUTLER'S GARTER SNAKE

The garter snake, †? Eutarnia but/en Cope, has been the sub ject of considerable discussion among herpetologists in spite of the fact that only five specimens were known. In 1888, Professor Cope (†89,p. 399) first recognized and described the species on the basis of a single specimen (Purdue Univ. Catalogue, No. 264) sent to him by Mr. A. W. Butler. This specimen was thought to have come from Richmond, Indiana, but it was un labeled when Mr. Butler received it from Purdue University, so it may or may not have come from there. In 1895, Mr. Reddick (†96,p. 261) took another specimen (Univ. of Ind. Cat. No. i io) at the Indiana University Biological Station at Turkey Lake, Kosciusko County, Indiana. There are two specimens in the museum of the Academy of Natural Sciences of Philadelphia (Cat. No. 6523) labeled by Professor Cope, which are described by Mr. A. E. Brown (†0!,p. 27) and credited by him to south eastern Indiana. But in a letter April 15, 1904, he says con cerning these specimens, “? Thelocality given is Miami river, which probably means Ohio.― The fifth specimen recorded (U. S. N. M. Cat. No. 21692) was collected by Mr. Philip Kirsch at Waterloo, Indiana, and is described by Dr. Stejneger (†94, pp. 593—594). Professor Cope examined the type and on the basis of its dis tinctive characters considered it a good species, a view supported by Dr. Stejneger after a study of the specimen from Waterloo, Indiana. Mr. Brown, however, upon a study of the two speci mens in the collection of the Philadelphia Academy of Natural Sciences, and for the reason that there were so few specimens known, considered them anomalies of E. sir/a/is sir/a/is, with considerable reason, for it seems as if four specimens (the speci men from Turkey Lake is described for the first time in this paper) is entirely too small a number upon which to form a spe cies. Particularly is this true in a genus like Eutcenia, in which