248 VOCABULARY. 



often diving for its food, which consists of insects and other 

 small aquatic animals. Johnson's N. U. Cyc. 



Of all the mammalia yet known, the Ornithorhynchus 

 seems the most extraordinary in its conformation, exhibiting 

 the perfect resemblance of the beak of a duck engrafted on 

 the head of a quadruped. Dr. Shaw. 



According to Ernst H. Haeckel, these animals "are be- 

 coming less numerous year by year, and will soon be classed, 

 with all their blood relations, among the extinct animals of 

 our globe." 



Os. A bone ; also a mouth. 



OSTEOL'OGY. The part of anatomy which treats of bones. 



OSTEO-SARCO'MA. Disease of the bony tissue, which consists in 

 softening of its laminae, and their transformation into a fleshy 

 substance, analogous to that of cancer, accompanied with 

 general symptoms of canc3rous affection. The word has also 

 often been used synonymously with 'spina ventosa.' 



O'v ARIES (ovum, egg). The two organs in oviparous animals 

 in which the ova, the generative product of the female, are 

 formed. They are termed by Galen ' testes muliebres,' since 

 they are in women the analogues of the testes in men. The 

 ovaries in adult women are situated on either side of the 

 uterus, in the iliac fossae ; they are included in the two pel- 

 vic duplicatures of the peritoneum, which are called the 

 broad ligaments. Each ovary is also attached by a round, 

 fibrous cord the ovarian ligament to the side of the uterus, 

 and by a lesser fibrous cord to the fringed edge of the Fallo- 

 pian oviduct. The ovary is an oblong, ovoid, flattened body, 

 of a whitish color and uneven surface. It is ^ to ^ an inch 

 thick, f of an inch wide, and 1 inch to 1 long ; it weighs 

 from 1 to 2 drachms. E. Darwin Hudson, Jr. 



OZE'NA. An affection of the pituitary membrane, which gives 

 occasion to a disagreeable odor similar to a crushed bed-bug. 

 P. 



PALEONTOI/OGY. The study of ancient beings. The science 

 which treats of the evidences of organic life upon the earth 

 during the different past geological periods of its history. 

 These evidences consist in the remains of plants and animals 

 imbedded or otherwise preserved in the rocky s rata or upon 

 their surfaces, and in other indications of animal existence, 



