Radial and central spines are variable in number from 4 to 21.

The central spines may be 1 to 2 centimeters long or more.

Now he swung down a seat from the central spine.

The one to three central spines, which can sometimes also be absent, are 1 to 3 inches long.

A typical areole may have one or a few long, sharp central spines, which serve as the primary defense.

Sometimes a central spine is present, but it usually lacks.

A road still runs up the central spine of the island serving the scattered empty houses.

Both men watched as the seven wooden eggs were brought out to the central spine of the track.

One of the central spines is hooked at its apex as well.

The turning posts weren't actually part of the central spine, Margo realized.