Students or researchers who are new to Wallace studies might want some guidance as to which of his works are best known and/or have been the most influential. This is actually rather difficult to objectively assess, but I can at least list those seven books and eight articles of his that have been cited the most times in the technical literature over the last fifty years or so (based on information gleaned from Science Citation Index, Social Sciences Citation Index, and Arts & Humanities Citation Index):

Books (in recent years the first three have been cited about equally most frequently):

1. Darwinism (S724: 1889). This is one of the best (if not the best) summaries of the state of Darwinism as of the late nineteenth century, describing both Darwin's positions and Wallace's own.

1. The Malay Archipelago (S715: 1869). This book, describing his travels in the East in the years 1854 to 1862, was Wallace's most successful work, literarily and commercially.

1. The Geographical Distribution of Animals (S718: 1876). This monumental two-volume accounting of "what lives where, and why" provided a firm foundation for the subsequent development of the field of zoogeography.

4. Island Life (S721: 1880). Many observers consider this Wallace's finest scientific effort. It treats two subjects: the causes and influences of glaciation processes, and the nature of insular biotas.

5. Tropical Nature, and Other Essays (S719: 1878). A set of essays on leading characteristics of tropical biology.

6. Contributions to the Theory of Natural Selection (S716: 1870). Early essays on the subject that made him famous.

7. My Life (S729: 1905). Wallace's lengthy (two-volume) and very interesting autobiography.

Articles (not in rank order--in recent years, these have all been cited reasonably frequently):

"The Origin of Human Races and the Antiquity of Man..." (S93: 1864). Wallace's application of the theory of natural selection to the special problem of racial differentiation.

"On the Tendency of Varieties to Depart Indefinitely from the Original Type" (S43: 1858). The famous 'Ternate essay' Wallace sent to Darwin containing the former's original elucidation of the theory of natural selection.

"On the Zoological Geography of the Malay Archipelago" (S53: 1859). Containing Wallace's original description of the faunal discontinuity that later was named after him: "Wallace's Line."

"On the Phenomena of Variation and Geographical Distribution as Illustrated by the Papilionidae of the Malayan Region" (S96: 1864). Containing early Wallace conclusions on such subjects as mimicry, polymorphism, and protective coloration.

"On the Monkeys of the Amazon" (S8: 1852). Includes Wallace's elucidation of the "riverine barriers" hypothesis of distribution patterns.

"Sir Charles Lyell on Geological Climates and the Origin of Species" (S146: 1869). Includes Wallace's first major public statement regarding his belief that natural selection cannot be held to account for all aspects of human evolution, attached to a long review of two of Lyell's works. Wallace's views as intimated in S146 were expanded into an essay entitled "The Limits of Natural Selection as Applied to Man" (S165: 1870) that was published as the last chapter of the collection Contributions to the Theory of Natural Selection (S716).

"On the Law Which Has Regulated the Introduction of New Species" (S20: 1855). In this pre-natural selection essay Wallace all but directly states his belief in an evolutionary interpretation of the meaning of geographical and geological patterns of species distribution.

"On the Physical Geography of the Malay Archipelago" (S78: 1863). Concluded by a famous passage that has become one of the most quoted writings in the literature of the biodiversity movement.