Each considered as a separate species and constituting perhaps the most complete description of these species published in English, Mr. H. H. Hume's characterization of the orange, sour orange, mandarin, pomelo, citron, lemon, and lime in his "Citrus Fruits and Their Culture," is here reproduced without alteration. Some writers have grouped several of these as subspecies under one great comprehensive species, but, as Mr. Hume aptly says: "What advantage is there in throwing the sour orange, sweet orange, pomelo, kumquat, and a few other distinctly different trees into one conglomerate species * * * and then placing each of the aforementioned plants under this species as subspecies and varieties. Such a procedure is more likely to result in further confusion than order." The species of the genus Citrus that have come under the observation of the writer, with two exceptions, seem naturally to divide themselves into two groups,--(1) those with more or less united filaments and hypogeal cotyledons, and (2) those with free filaments, and (in all instances where there has been an opportunity for observations) with supra-terraneous, distinct cotyledons (fig. 1). In so far as these characteristics have been observed in the Philippine citrus fruits, long and broad-winged petioles are a third correlative feature distinguishing group No. 2; C. ichangensis recently described by Swingle from China also possesses this last feature, but has connate filaments. The alsem and alemow seem to be intermediate between these forms, the alsem being most closely related to those in the first division, the filaments being connate, while the cotyledons in some lots that have been propagated appeared above ground. The alemow is most closely related to group No. 2, the filaments being nearly always free. The general character of the talamisan together with the presence of hypogeal cotyledons tends to the belief that this species has more or less united filaments and thus would belong to the first group. All descriptions have been made from living plant material either during tours of collection by the writer, or from plants grown at the Lamao experiment station from material sent to the Bureau of Agriculture from time to time since April, 1911. Also, all the material has been collected from plants growing in the yard of some Filipino and so may lay claim to having been domesticated. While this statement may not be altogether reliable it is interesting to note that in Bohol the Filipinos stated that the following trees grew wild in the forest: Among-pong, amontay, balincolong, biasong, canci, colo-colo, limoncito, limao, lombog, and samuyao.