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96 THE CONDOR Vol. XX more recent than that of the Subtropical zone; that the Pararno zone reaches sea lev- el still farther south and that its life is de- rived by latitudinal extension and is more recent than that of the Temperate zone; and that the present 'trend of the distribu- tion of life. upon the continent is north- ward, few boreal species having entered Co- lombia in recent geologic times. In other words, the hypothesis advanced is that the enormous mountain ranges forming so large a part. of the Colombian region arose as a gradually increasing elevation forced up- wards from a tropical base, the lofty sum- mits with their necessarily cooler climate being populated by the latitudinal extension of the range of species from regions to the northward and to the southward having similar climates, and also by "altitudinal ex- tension as the pressure of life from immedi- ately contiguous regions below forced spe- cies upward, the more adaptable of which survived". Three of the four zones are divided into faunai areas. In the Tropical zone five are recognized, as follows: Colombian-Pacific, Cauca-Magdaiena, Caribbean, Orinocan,'Am- azonian. In the subtropical zone there are two, West Andean and East Andean. The Temperate zone has strongly marked humid and arid divisions but does not appear to be otherwise divided. The Pararno is uniform in character. Each of these zonal and faunal divisions is treated in detail, the points made being illustrated with a wealth of half-tones, .maps, and diagrams, and tables of bird species. Not the least interesting and instructive of these graphic features are the maps illus- trating the ranges of representative species. Part one (pp. 3-169) is devoted to this de- scriptive and philosophic matter. Part two, with some introductory and explanatory matter, largely relative to classification and nomenclature, contains the systematic list of the species concerned. For the most part the comments on each are extremely brief, frequently a mere statement of localities, but even so, the'1285 species and subspe- cies included necessarily make a rather bulky volume. The whole report is one of intense inter- est, and the facts and theories concerned are presented in a most attractive and convinc- ing manner. The volume fairly teems with suggestions of problems to be followed up, in addition to the many ingenious and satis- factory explanations advanced for condi- tions as encountered. While naturally much of this does not touch directly upon work in North America, still one comes across oc- casional statements of fact or opinion that have a bearing upon our own studies as well as generalizations that are applicable every- where in faunal research. It is interesting to note that, quite differ- ent from conditions in North America, no evidence of altitudinal migration in any species was obtained in this country of strongly contrasting mountains and valleys. The explanation of this is doubtless to be found in the equable climatic conditions of each zone the year through. It is not so easy, however, to find an explanation of the fact that the many North American species encountered here in their winter home, pay absolutely no attention to faunal or zonal boundaries. This is decidedly at variance with conditions along the Pacific Coast of the United States, where the ranges of win- ter visitants from Alaska and northwestern Canada are strongly influenced by local cli- matic conditions. Of the many North American birds win- tering in or passing through Colombia near- ly all are eastern species. The Western Wood Pewee (Myiochanes richar?soni) is mentioned as the only bird of the western United States, but the systematic list of spe- cies also includes Chorgeiles acutipenngs texensis and Myiogynastes luteiventris, both of which occur in that region, whether or ?ot the Colombian migrants individually hail from within our boundaries. It seems curi- ous to read of a subspecies of our familiar Black Phoebe as "an inhabitant of the Trop- ical Zone but working up the streams to the lower border of the Subtropics", for one would expect it rather amid temperate zone surroundings. Dr. Chapman has much to say regarding classification and nomenclature, as well as the treatment of genera and subspecies, and what he says is clea1y and vigorousl? ex- pressed and worthy of careful consideration. In his strong advocacy of personal field work in a study of this sort he assumes a position that will certainly not be cornbated by 'any active western ornithologist. In fact it is a little difficult at this day to realize the need of argument to uphold such a self- evident proposition. It is but a thankless task to pick out min- or errors in a work of such high general standard, and really the volume under dis- cussion forms a most unprofitable field for such search. As an example of how errors creep in despite most careful proof reading,