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The protuberance through which milk is drawn from the udder or breast of a mammal; a nipple; a pap; a mammilla; a dug; a tit.

oral artery. Temporal bone, a very complex bone situated in the side of the skull of most mammals and containing the organ of hearing. It consists of an expanded squamosal portion above the ear, corresponding to the squamosal and zygoma of the lower vertebrates, and a thickened basal petrosal and mastoid portion, corre…

et, and olive." Fairholt. -- Tertiary period. (Geol.) (a) The first period of the age of mammals, or of the Cenozoic era. (b) The rock formation of that period; -- called also Tertiary formation. See the Chart of Geology. -- Tertiary syphilis (Med.), the third and last stage of syphilis, in which it invades the bones…

mian and Triassic formations in South Africa. In some respects they resembled carnivorous mammals. Called also Theromorpha.

in the throat, or in the neighboring region, of nearly all vertebrates. In man and other mammals it is the throat, or neck, sweetbread, which lies in the upper part of the thorax and lower part of the throat. It is largest in fetal and early life, and disappears or becomes rudimentary in the adult.

unknown function, in the floor of the mouth or the region of the larynx. In man and most mammals it is a highly vascular organ, partly surrounding the base of the larynx and the upper part of the trachea. -- Thyroid dislocation (Surg.), dislocation of the thigh bone into the thyroid foramen. -- Thyroid foramen, the…

ch articulates with the tibia and corresponds to a part of the astragalus in man and most mammals.

An extinct group of Mammalia found fossil in the Eocene formation. The species are related to the carnivores, ungulates, and rodents. Called also Tillodonta.

A large American Miocene mammal, allied to the rhinoceros, and more nearly to the extinct Brontotherium.

A gigantic extinct herbivorous mammal from South America, having teeth bent like a bow. It is the type of the order Toxodonta.

An extinct order of Mammalia found in the South American Tertiary formation. The incisor teeth were long and curved and provided with a persistent pulp. They are supposed to be related both to the rodents and ungulates. Called also Toxodontia.

flaps, at the opening of the right auricle into the right ventricle in the heart of most mammals; -- sometimes called the tricuspid valves, each flap being regarded as a valve.

A theory of the development of mammalian molar teeth. The primitive stage is that of simple cones, as in reptiles. The simple cone then developed a smaller cone in front and another behind. Next, a cingulum was developed, and the three cones became arranged in a triangle, the two smaller cusps having moved to the outer…

An extensive division of Mammalia including those having claws or nails, as distinguished from the hoofed animals (Ungulata).

An extensive group of mammals including all those that have hoofs. It comprises the Artiodactyla and Perissodactyla.

A very soluble crystalline body which is the chief constituent of the urine in mammals and some other animals. It is also present in small quantity in blood, serous fluids, lymph, the liver, etc.

id. Uric acid, a crystalline body, present in small quantity in the urine of man and most mammals. Combined in the form of urate of ammonia, it is the chief constituent of the urine of birds and reptiles, forming the white part. Traces of it are also found in the various organs of the body. It is likewise a common cons…

In mammals, a fluid excretion from the kidneys; in birds and reptiles, a solid or semisolid excretion.

The organ of a female mammal in which the young are developed previous to birth; the womb.

nd a ventral, or visceral, cavity below it. The subdivisions or classes of Vertebrata are Mammalia, Aves, Reptilia, Amphibia, Pisces, Marsipobranchia, and Leptocardia.