Limulus casts its cuticle several times during the first year—Lockwood estimates five or six times between hatching out in June and the onset of the cold weather. The cuticle splits along a “thin narrow rim” which “runs round the under side of the anterior portion of the cephalic shield.”[[220]] This extends until it reaches that level where the animal is widest. Through this slit the body of the king-crab emerges, coming out, not as that of a beetle anteriorly and dorsally, but anteriorly and ventrally, in such a way as to induce the unobservant to exclaim “it is spewing itself out of its mouth.” In one nearly full-sized animal the increase in the shorter diameter of the cephalic shield after a moult was from 8 inches to 9½ inches, which is an indication of very rapid growth. If after their first year they moult annually Lockwood estimates it would take them eight years to attain their full size.

The only economic use I know to which Limulus is put is that of feeding both poultry and pigs. The females are preferred on account of the eggs, of which half-a-pint may be crowded into the cephalic shield. The king-crab is opened by running a knife round the thin line mentioned on p. 275. There is a belief in New Jersey that this diet makes the poultry lay; undoubtedly it fattens both fowls and pigs, but it gives a “shocking” flavour to the flesh of both.

CLASSIFICATION.

But five species of existing King-crabs are known, and these are grouped by Pocock into two sub-families: (i.) the Xiphosurinae, and (ii.) the Tachypleinae. These together make up the single family Xiphosuridae which is co-extensive with the Order. The following is Pocock’s classification.[[221]] The names used in this article are printed in italic capitals.

Order Xiphosura.
Family 1. Xiphosuridae.
Sub-Fam. 1. Xiphosurinae.

This includes the single species Xiphosura polyphemus (Linn.) (= Limulus polyphemus, Latreille), “which is said to range from the coast of Maine to Yucatan.”

Sub-Fam. 2. Tachypleinae.

Genus A. Tachypleus includes three species: (i.) T. gigas, Müll. (= Limulus gigas, Müll., and L. moluccanus, Latreille), widely distributed in Malaysia; (ii.) T. tridentatus, Leach (= L. tridentatus, Leach, and L. longispina, Van der Hoeven), extending from British North Borneo to China and Southern Japan; and (iii.) T. hoeveni, Pocock (= L. moluccanus, Van der Hoeven), found in the Moluccas.