_Hominidæ._ This family of Anthropoidea includes only the human species (_Homo sapiens_). The dental formula is 2/2 1/1 2/2 3/3. The tail is not visible. The Hominidæ differ from the Simiidæ, structurally, mainly in the more perfect assumption of the erect attitude. There is a more complete adaptation of the pelvic limbs to bearing the weight of the body, correlated with compensating alteration in the curvature of the spinal column. The big toe (hallux) is not opposable, and also it is often longer, never shorter than the other toes, and is not abducted from them. He has a far better heel than the Simiidæ. The thumb is far more opposable in man. There is a greater length of the pelvic limbs compared with the pectoral limbs. The canine teeth are much smaller and do not project beyond the level of the others. The brain has a much greater size and complexity. Man has a larger forehead, smaller cheek bones, smaller supraorbital ridges, a less protrusive face, and a true, well-marked chin. The Simiidæ are subdivided into the two following groups, viz.: Sub-family 1.—_Hylobatinæ._ Genus 1.—_Hylobates_ (Gibbons). Sub-family 2.—_Simiinæ._ Genus 1.—_Simia_ (Orangs). Genus 2.—_Gorilla_ (Gorillas). Genus 3.—_Anthropopithecus_ (Chimpanzees). SYNOPSIS OF THE PLANT KINGDOM. GROUP A. PROTOPHYTA. GROUP B. METAPHYTA. The Metaphyta are subdivided into: 1. _Cryptogams_: Flowerless plants. 2. _Phanerogams_: Flowering plants. The Cryptogams are subdivided into: 1. _Thallophyta_: Seaweeds, Fungi, Lichens. 2. _Bryophyta_: Mosses, Liverworts. 3. _Pteridophyta_: Ferns, Horsetails, Clubmosses. The Phanerogams are subdivided into: 1. _Gymnospermæ_: Order a.—_Cycadaceæ_: Cycads. Order b.—_Coniferæ_: Pines, Spruces, Cypresses. 2. _Angiospermæ_: Class 1.—_Monocotyledones_: Grasses, Palms. Class 2.—_Dicotyledones_: Oaks, Poplars, Elms. SECTION VIII. WORKS OF REFERENCE. WORKS OF REFERENCE. The following books have been the constant companions of the author during the preparation of his “First Book in Organic Evolution”:—