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Mollusckque - Mollusk vs Mollusc
by Gary Rosenberg

Malacologists and conchologists often wonder whether "mollusk" or "mollusc" is the correct or preferred spelling of the vernacular name for the phylum Mollusca. A debate on the subject appeared in Hawaiian Shell News from April to July of 1993. Stu Lillico posed the question (April, p. 12), Dr. Robert Cowie (May, p. 4) stated that the American spelling "mollusk" was a recent change from "mollusc" used elsewhere in the world, and Richard E. Petit (July, p. 6) demonstrated that early British and American authors both used the spelling "mollusk," contrary to general assumption. Independently, a similar debate raged on the Mollusca discussion group on Internet from September 26 to October 6, 1993 (www.ucmp.berkeley.edu/mologis/mollusca.html). Attempting as usual to avoid undocumented opinions, Dr. Barry Roth commented that to properly understand the significance of the use of "mollusk" or "mollusc," we need more information on the distribution of the two morphs in time and space. I followed Barry's suggestion, posting to the discussion group my observations and conclusions, which form the basis of this article. I've also incorporated some of Dick Petit's findings, and additional items I've discovered since.

The Oxford English Dictionary, 2nd edition (OED) in its entry for "mollusc," records the first use in English as "mollusque" in 1783. The entry also records the spelling "mollusk" in Penny Cyclopedia vol. 14 in 1839; the first "mollusc" is by F. Francis in his book Angling in 1867. So, on the basis of priority in the OED, it appears that "mollusk" is older than "mollusc." The first appearance of the word mollusc in a book on angling, however, is suspicious, and a quick browse through the stacks of my institution's library found several earlier uses of "mollusc": T. Spencer Cobbold, The Treasury of Natural History, or a popular dictionary of zoology, 6th ed. (1862), D. M. Reese, Elements of Zoology, or a natural history of the animals (1849); and G. B. Sowerby, Jr., A Conchological Manual, p. 23 (1839). This leaves both "mollusk" and "mollusc" dating from 1839. "Mollusk" can be pushed back to 1837, however, in the Penny Cyclopedia vol. 7 (p. 434, entry for Conchology).

I submitted my findings on "mollusk" versus "mollusc" to the editors of the Oxford English Dictionary, who replied that searching the CD ROM version of their dictionary revealed quotations under other entries documenting earlier uses of both spellings. "Mollusc" appears in 1833 in Charles Lyell's Principles of Geology III, p. 230, and "mollusk" in 1836 in Robert B. Todd's Cyclopedia of Anatomy and Physiology I, p. 712. Since then, I've found "mollusk" in 1832, in Richard Owen's Memoir on the Pearly Nautilus, p. 29, where it is a direct translation of "mollusque" from an article by Cuvier. So, at the moment, "mollusk" (1832) has one year's priority on "mollusc" (1833), but earlier instances of both might yet be found.

The word "mollusk" probably was coined in response to growing acceptance of Cuvier's classification as set forth in his great work Regnè Animal (1817) which expanded the concept of "Mollusca" to include the bivalves and gastropods with the cephalopods. Possibly the spelling "mollusk" and "mollusc" have independent derivations. "Mollusk" as used by Owen (1832) is clearly an Anglicization of "mollusque," whereas "mollusc" could be a noun form of "molluscous" or a vernacular singular for the plural "mollusca." The only source I examined that used "mollusque" as an English word was Isaac Lea (1828, Transactions of the American Philosophical Society III, p. 260), again taken straight from Cuvier.

Although "mollusk" and "mollusc" both date from the 1830s, "mollusc" is the rarer word at least into the 1870s. Almost all British conchologists used the spelling "mollusk" until the 1860s: Swainson (1840), A Treatise on Conchology; Brown (1844), Illustrations of the Recent Conchology of Great Britain and Ireland; Johnston (1850), An Introduction to Conchology; Forbes & Hanley (1853), A History of British Mollusca; Reeve (1860), Elements of Conchology; Jeffreys (1867), British Conchology; Woodward (1851 ["mollusk" p. 31, 36, 44; "mollusc" on p. 18]), Manual of the Mollusca. Huxley (1877) even used "molluskigerous." Sowerby seems to be the only major author who favored "mollusc," although he used the word rarely. Some authors avoided the issue (e.g. Fleming and J. E. Gray) by using "Mollusca" or "molluscous animal" rather than "mollusk" or "mollusc." British malacologists probably started favoring "mollusc" in the 1870s: The Quarterly Journal of Conchology (vol. 1, 1874-1878), which became Journal of Conchology, used that spelling. Another possible influence is Charles Darwin, who used "mollusc."

British popular works on conchology also favored the spelling "mollusk": M. Roberts (1851), A Popular History of the Mollusca; M. S. Lovell (1867), The Edible Mollusks of Great Britain and Ireland with recipes for cooking them; [E. Mayo] (1846), Lessons on shells as given to children between the ages of eight and ten, in a Pestalozzian school, at Cheam, Surrey, 3rd ed. (The first edition used "mollusca"; I haven't seen the second edition). Among the popular works I've examined, only A. Catlow (1843), Popular Conchology used "mollusc." The Imperial Dictionary, John Ogilvie, ed. (1852), published in Edinburgh and London lists "mollusk" with no alternate spelling.

Today it is well established that "mollusk" is the American spelling, and "mollusc" is the British spelling. For example, the British Collin's Dictionary of the English language, 2nd ed. (1986), gives "mollusk" as the U.S. spelling of "mollusc." The Columbia Encyclopedia, the standard American one volume encyclopedia (3rd ed., 1963), doesn't even mention an alternate spelling of "mollusk." "Mollusk" first appears in one of Noah Webster's dictionaries in 1854. The alternate spelling "mollusc" is not listed until 1961 (3rd unabridged edition). The first dictionary published in the United States that mentions "mollusc" as an alternate spelling of "mollusk" appears to be The Century Dictionary and Cyclopedia (1889). There are of course American works that use the spelling "mollusc" before 1900, but they are rarities, e.g., Zell's Popular Encyclopedia (1871), published in Philadelphia.

So, which is correct, "mollusk" or "mollusc"? I favor mollusk, because it is formed in accordance with accepted standards of English orthography. Many English words end in -sk, but only a few end in -sc. The OED includes five: disc, fisc, lantisc, panisc, and subfusc, all of which have variant or preferred spellings ending in -sk. "Disk," from Latin discus, is preferred to "disc": the OED says "An earlier and better spelling is disk, but there is a tendency to use disc in some scientific senses." "Fisc" (the public, state or royal treasury) is preferred to "fisk," except in Scottish law, but the word is now rare. "Lantisk" (the mastic tree) is now preferred over "lantisc," and "panisc" (a little Pan), is rare, with a single quotation in 1850 balancing one in 1604 for "panisk." "Subfusk" (dusky, dull, somber) was the dominant spelling from 1710 to 1900, with "subfusc" winning out in the 20th century from its first appearance in 1883. Among common English words, "mollusc" and "disc" are the only exceptions to the general pattern of derivation of -sk words from Latin and French:

Latin French
asteriscus = asterisk casque = cask
basiliscus = basilisk frisque = frisk
Damascus = damask masque = mask
flasco = flask risque = risk
muscus = musk  
obeliscus = obelisk  

Asterisk, basilisk, damask, and obelisk all had variant spellings with -sc endings in previous centuries, but have now standardized on the -sk ending. The preference for -sk endings in English may reflect the Germanic affinities of the language. The continued persistence of the -sc spelling of "mollusk" probably results from its coexistence with the words "molluscan" and "Mollusca"; just as the continued existence of "disc" correlates with the existence of "discoidal." The other words derived from Latin listed above do not have common adjectival forms that would allow persistence of -sc endings.

I'll conclude with an analogy to the divergence of populations of a species. Imagine the word "mollusk" evolving in England. The word is polymorphic, with variants "mollusk" and "mollusc," the latter being less common initially. The word "mollusk" dispersed to the United States, but "mollusc" did not. Subsequently, "mollusc" increased in frequency in Great Britain, displacing "mollusk," and then propagated to other parts of the world as malacological traditions were established in South Africa, Australia and elsewhere. As English has become the primary language of science, many European scientists have adopted it, generally using British English because of proximity. Since "mollusc" is now (probably) more widespread and common globally than "mollusk," people have assumed that it was always the common form and that "mollusk" evolved from it in the United States. In fact, "mollusk" was formerly the dominant form even in England. Similar misinterpretations often happen in attempts to figure out the evolutionary relationships of species, but careful analysis of characters generally reveals the underlying patterns.

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This article was published in the September 1996 issue of American Conchologist.

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