"The first two volumes, devoted to shells of the South Seas, were originally published as a separate work in 1784. Martyn then extended the work to four volumes with an additional 80 plates. ‘From the introduction to The universal conchologist we learn that it was 'to commence with the figures of shells (most of them rare and nondescript) which have been collected by several officers of the shipsunder the command of Captain Byron, Wallis, Cook, and others made to the South Sea' ... When the Resolution and the Discovery returned from the third and last voyage in 1780 [the dealer] Humphrey purchased some more shells, but the bulk of the conchological spoils went this time to Thomas Martyn, a knowledgeable dealer, versatile writer and gifted artist ... Unlike Humphrey and other dealers who snapped up the Cook shells Thomas Martyn had more than a pecuniary interest in his purchases. Martyn’s reason for wanting to corner the market in South Seas shells was entirely praiseworthy; although he sold many of the shells he had bought, he illustrated the finest in The Universal Conchologist, his magnum opus [and] a work which, for beauty, has seldom been surpassed in the history of conchological iconography’ (Dance, A history of shell collecting).

"Martyn purchased shells brought back from Cook’s third voyage, although, as he wrote to Henry Seymer on 9 December 1780, ‘I have purchased, amounting to 400 gns, more than 2 thirds of the whole brought home, Nevertheless I do not abound either in the variety of the new or many duplicates of the known ones that are valuable’. As a result, he modified his project and instead of presenting two shells on each plate, presented only one but depicted in two different views. Besides the specimens deriving from Cook’s voyages, Martyn included specimens from the collections of the Duchess of Portland, the Countess of Bute, John Hunter, the Forsters, and others. The fine plates were drawn by Martyn and engraved and coloured by his 'Academy' of young men whom he had trained as natural history artists. The plates, each showing a single species in two positions, were engraved in soft aquatint and printed lightly inked, so that when hand-coloured they would resemble watercolours" (William P. Watson, Science, medicine and natural history books exhibited at the New York International Antiquarian Bookfair...2020).