Sclerophyllous leaves are ually characterized by entire or sub-entire margins, a thick cuticle, riall but rarely sunken stomata, a we1l-developed and close-set ilisade tissue and a feeble system of air-spaces.
In these, as in Patella, the typical ctenidia are aborted, and the branchial function is assumed by close-set lamelliform processes arranged in a series beneath the mantle-skirt on either side of the foot.
Only here and there upon its fringe the identity of this great area with the metropolis is lost to the eye, where open country remains unbroken by streets or close-set buildings.
They are covered with a fur to which they owe their chief commercial value; this consists of two kinds of hair - the one close-set, silky and of a greyish colour, the other much coarser and longer, and of a reddish brown.
The polar or white bear (Ursus maritimus), common to the Arctic regions of both hemispheres, is distinguished from the other species by having the soles of the feet covered with close-set hairs, - in adaptation to the wants of the creature, the bear being thereby enabled to walk securely on slippery ice.