The Ladybird book Sea and Air Mammals is from Series 691 - Animals of the World and was published in 1972. Each of the other books in the series looks at the mammals living in all the different continents (except for Antarctica for some reason). Full colour illustrations are provided by John Leigh-Pemberton, a map at the beginning shows the distribution of these mammals and at the back of the book there is a chart showing the Orders of Mammals referred to, arranged in families.
From that introduction you can probably surmise that this is not one of the Ladybird books which is aimed at very young children. Instead it's a substantial reference work, which goes into an enormous amount of detail. It's very wordy, and although the text is fairly easy to read and contains plenty of interesting facts about these mammals, it's not a book that you would sit and read through. Instead I imagine it is intended for the school or home reference library, waiting for a particular piece of relevant homework.
Like all Ladybird books, it's the illustrations that really stand out. Some of the mammals are represented in their natural surroundings, others are drawn on the page in families so that you can compare them. One of the bats is drawn as a labelled diagram. I can easily imagine copying the pictures out to illustrate a school project.
It will definitely be a useful reference tool to have around, and much nicer to thumb through than scrolling past information on Wikipedia!
I'm joining in with Ladybird Tuesday at Being Mrs C. You can see all my previous Ladybird Tuesday posts here.