Harvey’s original intention, published in a Subscription Prospectus in 1853 before he left on his world tour, was to offer for sale via subscription the excess specimens of the algae that he would collect (the specimens that were not required by the Herbarium at Trinity). It was planned that subscribers would receive Australian specimens, as they were so little known and as Australian shores were known to be “rich in varied and curious forms of Algae”.2 The specimens would be collected and preserved by Harvey or under his immediate supervision and would be mounted on white paper, numbered and provided with the habitat and a provisional name. The Subscription Prospectus stated that there would be approximately fifty sets available for subscribers, but that at that stage, it was impossible to state exactly how many species would be included, although the number was likely to be between 200 and 600.3
There is no doubt that Harvey’s subscribers added considerably to his workload. In one letter home he states that: “… sea plants take so much time in washing, laying out, and changing, that my whole time is literally occupied, except at meals; and one day’s walk sometimes takes me three days to put on paper. This is because I have to dry such a number of specimens of each kind for my seventy subscribers.” 4
The subscription sets of Harvey’s duplicate algae specimens are known as the Exsiccatae; ultimately there were 601 Australian species of algae, 106 species from Ceylon (Sri Lanka) and 124 from the Friendly Islands (Tonga). It seems though, that each version of the Exsiccatae is unique, and contains different numbers and types of specimens.
The Exsiccatae were sold and distributed around the world to private collectors, botanists, philanthropists, naturalists, herbaria and museums. There are four known in New South Wales (from the Sydney Herbarium and the Mitchell Library) and one at the Melbourne Herbarium.5 The Exsiccatae owned by Deakin University Library has come via the collection of the Corning Library and the Garden Centre of Cleveland. Its original subscriber is unknown. Deakin’s example contains 225 specimens of Australian algae (from a potential total of 601), fifty one specimens from Ceylon and thirty nine from the Friendly Islands. Of the Australian specimens, at least forty two have been described and labelled by Harvey as being a ‘new species’. Deakin’s Exsiccatae is bound, with a hand written title page, and contains 133 hand numbered pages. Each of the specimens is mounted on white paper which in turn has been mounted on a page. The specimens are almost all identified with handwritten names and numbers, which correspond to the list included at the front of the book, which also provides the species location guide.
Harvey also maintained a set of specimens for his own use whilst travelling. This was his working collection that he used for reference and to assist in describing his findings. These travelling sets are now located in the Herbaria of Trinity College in Dublin and the Royal Botanic Gardens in Melbourne. These sets, particularly those held at Trinity, are significant as they hold many examples of what are known as type specimens. Harvey realised that he was discovering many new examples of genera and species that were previously unknown to science.6 Whenever a new species is identified and described, a single specimen must be designated as a type (or holotype). It is the specimen from which comparisons can be made, to correctly identify all future examples of that species. Arguably, the specimens within the Exsiccatae that have the same locality and collection details are the same as the type specimens, thus can be known as isotypes.7