BY THE REV. J. E. TENISON-WOODS. 231 



times. The period is so remote that it makes us wonder to meet 

 with even two survivors, which are all the king-crabs known to be 

 living to the pi^esent day. The remarkable variations of the 

 typical structure can be seen by referring to any of the recent 

 works on palaeontology, where the forms of Prestwichia, Neo- 

 limulus, and Bellinurus, while preserving the likeness, most 

 cuiiously modify the details. 



A Limulus shell is divided into three parts ; the cephalic, the 

 abdominal, and the sword-like tail. The head is protected above 

 by a semicircular dome-like shield, on the upper part of which 

 are fixed a pair of compound and a pair of simple eyes ; below it 

 has six pairs of legs, the first pair bent upwards, each having 

 clav^^s or nippers at the end, with masticating jaws at the base. 

 The abdomen is pi-otected above by a six-sided shield. Below this 

 are six pairs of leaf-like appendages which carry gills and are used 

 for swimming, while the first pair is an operculum which overlaps 

 and protects the rest. To this is appended the long and sword- 

 like tail. The Malay name is Balancar. 



Iving-ci"abs are by no means uncommon in the Malaysia. I 

 have obtained many specimens from the Malays, the largest being 

 about two feet in length, which came from Cuyo in the Philippine 

 Islands. It is a burrowing animal which delights to thrust its 

 shield under the mud in shallow water. It shovels away the 

 slime on each side of it, using its tail as a fulcrum, while its legs 

 pick up its food in the shape of worms, small crustaceans, and 

 other organisms, which are disinterred by its excavations. '^- 



*Mr. Alexander Agassiz writes as follows to the " Sillimans Journal ": — 

 " Mr. C. D. VValcott has called attention to the fact that when collecting- 

 fossils he finds large numbers of Trilobites on their back (Ann. Lye. Nat. 

 Hist., N.Y., Vol. XI., p. 155, 1875. Twenty-eighth Report, N.Y. State 

 Museum, Dec. 1876.) From this he argues that they died in tlicir natural 

 position, and that, when living, they probaljly swam on tlieir backs He 

 mentions, in support of his view, the well-known fact that very young 

 LirfiuLwi and other Crustacea frequently swim in that position. I have, for 

 several summers kept young horseshoe crabs in my jars, and have noticed 

 that besides tims often swimming on their backs, tliey will remain in a 



