Many readers will already be familiar with James T. Costa's superb Harvard edition of Darwin's Origin of Species (2011). Costa turned this seminal text into an eminently understandable and readable work very firmly placed in modern-day scholarship. It is thus exciting to see him turn his annotating attention to Darwin's co-discoverer of natural selection, Alfred Russel Wallace. This particular work looks at Wallace's ‘Species Notebook’ (as Lewis McKinney described it), written during his time in the Malay Archipelago (1854–1862), which spawned not only his seminal papers on evolution and natural selection but also his best-selling travelogue, The Malay Archipelago (1869).

This notebook (one of a series) is, as Costa describes in his preface, ‘now among the crown jewels of biology’ (p. ix). Despite this, it has not received attention commensurate with its importance. However, the ‘Species Notebook’ Costa has focused upon is not an entirely easy manuscript to read by itself. Setting aside the legibility of the handwriting (which is actually rather good), the work was, as Costa explains, ‘more like a commonplace book’ (p. 5). Thus it contains a varied diet of text: from lists of species collected to extensive philosophizing or narrative pieces, and from pasted newspaper cuttings to diagrams on how to construct a display case for his collections. Consequently the annotations, unlike those to the Origin, are there not just to supplement the text, but rather to make sense of it.

Costa succeeds very well at this challenging task. He has been both judicious and thorough in choosing where and when to provide editorial insertions. These show the sheer volume of what could be termed both the superficial and the deep scholarship that he brings to bear on the text. By superficial – not meant in a pejorative sense – I mean simply that which helps smooth the reading of the notebook: the careful cross-referencing of discussions and themes that Wallace returns to, as well as explanations of the less familiar Victorian idioms which occasionally emerge. However, it is the deep scholarship that really impresses. Costa continuously engages in a direct discussion with the text. His background as an evolutionary biologist is apparent throughout, as he pulls Wallace's comments into the context of current scholarly debate. Yet his discussion with the source as a historian is equally impressive. Every opportunity is taken to enhance the text by using even the most insubstantial reference to an individual or theory as a point of departure to expand the reader's understanding beyond what is being discussed most immediately. What Costa does particularly well is align Wallace's comments and thinking with those of Darwin. Costa displays the close affinities between Wallace's private discussions and what eventually emerged in Darwin's Origin. This highlights the remarkable level of intellectual convergence between the two great men. What becomes apparent is that if indeed a book was in Wallace's mind, its contents would have been very similar to Darwin's Origin.

The sheer diversity of material covered in this work makes summarizing it a difficult task. However, some themes do emerge clearly. Examples include Wallace the collector and field naturalist, seen through his notes on the orang-utan. We see him observing them, hunting them and – in the case of one infant – raising them. Then we turn to Wallace the evolutionary philosopher, as he actively engages with Charles Lyell's Principles of Geology and his views on transmutation, in the course of which, as Costa explains, he tried to ‘out-Lyell Lyell’ (p. 131). Wallace later muses on the distinction between species and varieties. Subsequently, he changes tack, turning his eye towards man with an ethnographical study of the people he encountered. Wallace then begins exploring some more practical proposals. For example, he considers radical ways to halt and reverse the proliferation of synonyms, and the formation of a practicable central natural-history library. What is apparent is that the value of this work goes far beyond those with an interest exclusively in Wallace. Its pages contain material of remarkable value and interest to historians of science of all persuasions, suggesting that to consider it as just the ‘crown jewels of biology’ is to render it an injustice.

Critical to the significance of such a resource is the supplementary material included to help the reader navigate the text. Here again the work must be highly praised. The appendices include a thematic section directing the reader to the various evolutionarily important discussions in Wallace's notebook. These include discussions of design, distribution, affinity, transmutation, instinct and humans. Despite its shortness, this appendix is a hugely worthwhile addition. What is more, Costa includes a longer and more discursive appendix on Wallace's interactions with Lyell throughout the notebook. Again, this is important and will hopefully begin the process of refocusing attention towards the centrality of Lyell in Wallace's intellectual Weltanschauung during this critical period.

The all-important index in such a non-linear text is thorough and well organized. However, one criticism is that the index only directs the reader to references in Wallace's original manuscript. The reasoning for this is clear: the focus is on Wallace's discussion. And from a practical point of view, the inclusion of the annotations would have perhaps made such an index too unwieldy. However, this does mean that the reader may overlook the hugely significant comments made by Costa in support of the manuscript. That is a great shame. Thus the inclusion of additional indexing for the annotations would have been greatly appreciated, especially when such a text usually finds itself dipped into rather than read from cover to cover.

Overall, this is a superb work which places one of the ‘crown jewels of biology’ proudly and prominently before the scholarly public at large. Consequently, it should find its way onto the shelves of a vast array of individual scholars and libraries in the history of science and beyond.