The distribution of the king-crab (Limulus Polyphemus) on our coast is very wide: it ranges from a point between the mouths of the Ken nebec and Penobscot rivers of Maine to Mexico, the Spanish 'Alain. and the West Indies, seeming to attain its greatest size at Cape Hatteras and on the Delaware and New Jersey shores. The five existing species of Limulus (one American and four Asiatic) have been recently divided by Pocock and also by Packard into three genera. One species of Tachypleus ( TaehypIrus tridenta ins) abounds in Southern Japan and the Chinese seas; another (Tackapleus Molureanus) inhabits the Molucca Islands. Formosa. the Philippines, and Southern China ; and Tarhypleus gigns, Ma laysia• Gulf of Siam. Singapore, and Torres Straits. Carcinoseorpius rotundirauda (Latr.) occurs in the Mohueea and Philippine Islands., Siam, and Malaysia. This last-named geniis is the most primitive form. all the head-appendages ending in forceps much like those of the female; while the most specialized 101111 is Tachypleus, in which the second and third feet end in for ceps; Limulus Polyphemus is intermediate be tween the None has survived in Europe and other parts of the world except as stated above.
The systematie position of the king-erab is unsettled, but it is allied to the trilobites on the one hand and to the arachnids (scorpions) un the other. It repre-ents, .according to Packard, a class (Merostomata of Dana) which is inter mediate between the trilobites and the Arach nida• with no near affinities to the Crusta eea. Limulns is an ancient form, of great vital ity, withstanding exposure for a day or two to the dry air or sun, and is an example of a per sistent type.
Allied to the order Niphosurn, of which Limn lus is the type, is the order Eurypterida. a group of fossil form, ranging from the Cambrian to the end• of the Carboniferous. It is represented by Eurypterus, Pterygotus, Slimonia. etc. (See I EROSTONIATA ) The family to which Limulus belongs began to flourish in the Devonian, and the Limulus of the Jurassic and present times was represented in the Carboniferous period by small king-crabs (Prest•ielda, Belinurus) which were scarcely over two inches in length.