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The Algonkian period or era, or system or group of systems.

t of the northern and eastern part of North America. The name was originally applied to a group of Indian tribes north of the River St. Lawrence.

on consisting of large whitish or grayish globular cloudlets with shaded portions, often grouped in flocks or rows.

A group of large, extinct, herbivorous mammals, common in the Tertiary formation of the United States.

A group of insects which do not undergo any metamorphosis. [Written also Ametabolia.]

d atom or radical. Acid amide, a neutral compound formed by the substitution of the amido group for hydroxyl in an acid.

o acid, an acid in which a portion of the nonacid hydrogen has been replaced by the amido group. The amido acids are both basic and acid. -- Amido group, amidogen, NH2.

he molecule of which one of its hydrogen atoms has been removed; -- called also the amido group, and in composition represented by the form amido.

An extensive group of fossil cephalopods often very abundant in Mesozoic rocks. See Ammonite.

That group of vertebrates which develops in its embryonic life the envelope called the amnion. It comprises the reptiles, the birds, and the mammals.

rtebrates, having neither brain, skull, vertebræ, nor red blood. It forms the type of the group Acrania, Leptocardia, etc.

A numerous group of fourteen -- footed Crustacea, inhabiting both fresh and salt water. The body is usually compressed laterally, and the anterior pairs or legs are directed downward and forward, but the posterior legs are usually turned upward and backward. The beach flea is an example. See Tetradecapoda and Arthrostr…

or occupy in a pleasant manner; to stir with pleasing or mirthful emotions; to divert. A group children amusing themselves with pushing stones from the top [of the cliff], and watching as they plunged into the lake. Gilpin.

One of a group of metameric hydrocarbons, C5H10, of the ethylene series. The colorless, volatile, mobile liquid commonly called amylene is a mixture of different members of the group.

One of the starch group (C6H10O5)n of the carbohydrates; as, starch, arabin, dextrin, cellulose, etc.

A group of teleostean fishes destitute of spiny fin-rays, as the cod.

An organ which is equivalent in its functions to a different organ in another species or group, or even in the same group; as, the gill of a fish is the analogue of a lung in a quadruped, although the two are not of like structural relations.

alytical table (Nat. Hist.), a table in which the characteristics of the species or other groups are arranged so as to facilitate the determination of their names.

er these there are Classes, Orders, Families, Genera, Species, and sometimes intermediate groupings, all in regular subordination, but variously arranged by different writers.

A group of herbivorous mammals characterized by having the hoofs in a single series around the foot, as the elephant, rhinoceros, etc.