As to the origin of the technical name; ἀστακός, _astakos_, was the name by which the Greeks knew the lobster; and it has been handed down to us in the works of Aristotle, who does not seem to have taken any special notice of the crayfish. At the revival of learning, the early naturalists noted the close general similarity between the lobster and the crayfish; but, as the latter lives in fresh water, while the former is a marine animal, they called the crayfish, in their Latin, _Astacus fluviatilis_, or the “river-lobster,” by way of distinction; and this nomenclature was retained until, about forty-five years ago, an eminent French Naturalist, M. Milne-Edwards, pointed out that there are far more extensive differences between lobsters and crayfish than had been supposed; and that it would be advisable to mark the distinctness of the things by a corresponding difference in their names. Leaving _Astacus_ for the crayfishes, he proposed to change the technical name of the lobster into _Homarus_, by latinising the old French name “_Omar_,” or “_Homar_” (now _Homard_), for that animal. At the present time, therefore, while the recognised technical name of the crayfish is _Astacus fluviatilis_, that of the lobster is _Homarus vulgaris_. And as this nomenclature is generally received, it is desirable that it should not be altered; though it is attended by the inconvenience, that _Astacus_, as we now employ the name, does not {14} denote that which the Greeks, ancient and modern, signify, by its original, _astakos_; and does signify something quite different. Finally, as to why it is needful to have two names for the same thing, one vernacular, and one technical. Many people imagine that scientific terminology is a needless burden imposed upon the novice, and ask us why we cannot be content with plain English. In reply, I would suggest to such an objector to open a conversation about his own business with a carpenter, or an engineer, or, still better, with a sailor, and try how far plain English will go. The interview will not have lasted long before he will find himself lost in a maze of unintelligible technicalities. Every calling has its technical terminology; and every artisan uses terms of art, which sound like gibberish to those who know nothing of the art, but are exceedingly convenient to those who practise it. In fact, every art is full of conceptions which are special to itself; and, as the use of language is to convey our conceptions to one another, language must supply signs for those conceptions. There are two ways of doing this: either existing signs may be combined in loose and cumbrous periphrases; or new signs, having a well-understood and definite signification, may be invented. The practice of sensible people shows the advantage of the latter course; and here, as elsewhere, science has simply followed and improved upon common sense. {15}