2/6 ARACHNIDA XIPHOSURA CHAP. 



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 9 J 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 u 

 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 Xipho- 

 surinae, 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. 1 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 Xiplt osura polypliemus (Linn.) 

 ( = LIMULUS POLYPHEMUS, Latreille), "which is said to range 

 from the coast of Maine to Yucatan." 



Sub-Fam. 2. Tachypleinae. 



Genus A. Tacliypleus includes three species : (i.) T. gigas, 

 Miill. ( = Limulus gigas, Miill., and L. MOLUCCANUS, Latreille), 

 widely distributed in Malaysia ; (ii.) T. tridentatus, Leach 

 (^=L. tridentatus, Leach, and L. LONGISPIXA, Van der Hoeven), 

 extending from British North Borneo to China and Southern 



1 For a diagnosis of the species and a list of synonyms, see Pocock, Ann. 

 Not. Hist. (7), is., 1902, p. 256. 



