42 ELEMENTS OF BIOLOGY. 



Each half of the lower jaw composed of several pieces. Appendages of 

 the skin in the form of horny scales or bony plates. 



CLASS D. AVES (Birds). Respiratory organs in the form of lungs. 

 Lungs connected with air-receptacles placed in various parts of the 

 body. Heart four-chambered. Blood warm. Skull connected with 

 the backbone by a single articulating surface or " condyle." Each half 

 of the lower jaw composed of several pieces. Appendages of the skin 

 in the form of feathers. Fore-limbs converted into wings. Animal 

 oviparous. 



CLASS E. MAMMALIA (Quadrupeds). Breathing organs in the form 

 of lungs, which are never connected with air-receptacles placed in 

 different parts of the body. Heart four-chambered. Blood warm. 

 Skull connected with the backbone by two articulating surfaces or 

 " condyles." Each half of the lower jaw composed of a single piece. 

 Appendages of the skin in the form of hairs. Young nourished by 

 means of a special fluid the milk secreted by special glands the 

 mammary glands. Animal viviparous. 



VEGETABLE KINGDOM. 

 SUB-KINGDOM I. CRYPTOGAMS. 



Plants destitute of true flowers with stamens and pistils. No true 

 seeds, but simple cellules or " spores," in which there is no embryo 

 prior to germination. 



CLASS I. THALLOPHYTA. Stem and foliage undistinguishable, com- 

 posed of cellular tissue only. Ex. Lichens, Algae, and Fungi. 



CLASS II. ANOPHYTA. Stem and foliage distinct or confluent, of 

 cellular tissue only. Ex. Mosses and Liverworts. 



CLASS III. ACROGENS. Stem with woody tissue and vessels, growing 

 at its summit, and usually with distinct foliage. Ex. Horse-tails, Club- 

 mosses, Ferns. 



SUB-KINGDOM II. PHANEROGAMS. 



Plants producing true flowers with stamens and pistils. True seeds 

 containing an embryo. 



SECTION A. MONOCOTYLEDONES. Seeds with one cotyledon or seed- 

 leaf. Stems " endogenous" luith no manifest distinction into bark, wood, 

 and pith. 



CLASS I. ENDOGENS. Leaves parallel-veined, permanent. Root 

 like the stem internally. Ex. Palms, Lilies, Grasses. 



CLASS II. DICTYOGENS. Leaves net-veined, deciduous. Root 

 with the wood in a solid concentric circle. Ex. Sarsaparilla. 



