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A subdivision of a genus, comprising one or more species which differ from other species of the genus in some important character or characters; as, the azaleas now constitute a subgenus of Rhododendron.

A subdivision of a group, as of animals. Darwin.

Situated over or above a trochlea or trochlear surface; -- applied esp. to one of the subdivisions of the trigeminal nerve.

In Canada, one of the subdivisions of a county.

ng between the Boreal and Sonoran zones of North America. It includes an eastern or humid subdivision and a western arid one of corresponding temperature comprising the northern Great Plains and the lower slopes of the mountains of the western United States and Mexico. Called also Neutral zone.

A subdivision in the lower Silurian system of America; -- so named from Trenton Falls, in New York. The rocks are mostly limestones, and the period is divided into the Trenton, Utica, and Cincinnati epochs. See the Chart of Geology.

e pinnately cleft; -- said of a pinnatifid leaf when its segments are pinnatifid, and the subdivisions of these also are pinnatifid.

One of the subdivisions into which the Upper Cretaceous formation of Europe is divided.

Of, pertaining to, or designating, a subdivision of the Trenton Period of the Lower Silurian, characterized in the State of New York by beds of shale.

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

The middle subdivision of the Upper Silurian in Great Britain; -- so named from the typical locality in Shropshire.