GLOSSARY 465 



Sacral. — Belonging to the sacrum, or the bone composed usually of two 

 or more united vertebrae to which the sides of the pelvis in 

 vertebrate animals are attached. 



Sarcode. — The gelatinous material of which the bodies of the lowest 

 animals (Protozoa) are composed. 



ScuTELL^. — The horny plates with which the feet of birds are gen- 

 erally more or less covered, especially in front. 



Sedimentary Formations. — Rocks deposited as sediments from water. 



Segments. — The transverse rings of which the body of an articulate 

 animal or Annelid is composed. 



Sepals. — The leaves or segments of the calyx, or outermost envelope 

 of an ordinary flower. They are usually green, but sometimes 

 brightly colored. 



Serratures. — Teeth Hke those of a saw. 



Sessile. — ^Not supported on a stem or footstalk. 



Silurian System. — A very ancient system of fossiliferous rocks be- 

 longing to the earlier part of the Palaeozoic series. 



Specialization. — The setting apart of a particular organ for the per- 

 formance of a particular function. 

 .,^. Spinal Cord. — The central portion of the nervous system in the Verte- 

 I^K brata, which descends from the brain through the arches of the 

 ^Ir vertebrae, and gives off nearly all the nerves to the various organs 

 of the body. 



Stamens. — ^The male organs of flowering plants, standing in a circle 

 within the petals. They usually consist of a filament and an anther, 

 the anther being the essential part in which the pollen, or fecun- 

 dating dust, is formed. 



Sternum. — The breast-bone. 



Stigma. — The apical portion of the pistil in flowering plants. 



Stipules. — Small leafy organs placed at the base of the footstalks of 

 the leaves in many plants. 



Style. — The middle portion of the perfect pistil, which rises like a 

 column from the ovary and supports the stigma at its summit. 



Subcutaneous. — Situated beneath the skin. 



Suctorial. — Adapted for sucking. 



Sutures (in the skull). — The lines of junction of the bones of which 

 the skull is composed. 



Tarsus (pi. Tarsi). — The jointed feet of articulate animals, such as 



insects. 

 Teleostean Fishes. — Fishes of the kind familiar to us in the present 



day, having the skeleton usually completely ossified and the scales 



homy. 



