As primary grade readers have already been exposed to Life in a Bucket of Soil and. . . A Drop of Water, and Ross herself showed us Who Lives in This Log (1971), it's not surprising that she now closes in on cracks and crannies. The currently popular ecosystem approach is stretched a bit here as the cracks and crannies--defined as ""leftover places where some plants and animals manage to live and even flourish""--occur both in city sidewalks and on high mountains. In a format reminiscent of the Crowell Let's Read and Find Out science books, Ross mentions--and Wheatley pictures--not only plants (plaintain, dandelion, ferns and mosses) and tiny animals such as ants, snarls and spiders but also rats and mice, marmots and ""guinea-pig-sized"" pikas who make such niches their home base. Ross' wide pan allows for little more than a quick glance at each species, though it might prompt readers to look for other examples near home.