PjECILOPODA. 319 



twenty-two feet; the first ten, with the exception of the two anterior 

 ones in the males, are terminated by a dydactyle forceps, and in- 

 serted, as well as the two that follow, under a large semi-lunar 

 shield. They are wandering animals, and form the genus 



LIMULUS, Fab. 



The species are known in commerce by the name of the Molucca Crab. 



These animals are sometimes found two feet in length, they inhabit the 

 seas of hot climates, and most generally frequent their shores. They appear 

 to me to be proper to the East Indies and the coast of America. The spe- 

 cies found in France L. cydops is commonly called the Casserok,(l') 

 from its having some resemblance to the form of that utensil, and because 

 when the feet are removed its shell is used to hold water. Savages employ 

 the stylet of the tail to point their arrows, which, thus armed, are much 

 dreaded. Their eggs are eaten in China. When these animals walk, their 

 feet are not seen. Fossil specimens are found in certain strata of a mode- 

 rate antiquity. 



FAMILY II. 



SIPHONOSTOMA. 



The Siphonostomas have no kind of jaws whatever. A sucker or 

 siphon, sometimes external and in the form of an acute inarticulated 

 rostrum, and at others concealed or but slightly visible, fulfils the 

 functions of a mouth. There are never more than fourteen feet 

 The shell is very thin and composed of a single piece. They are 

 all parasitical. 



This family is now divided into two tribes, the CALAGIDES, com- 

 prising Argula and Caligus (or the Fish-Louse), and the LERNEI- 

 FORMES, which consists of two genera also. They are Dichelestium 

 and 



NICOTHOE. 



These animals terminate the Crustacea, and are distinguished from all others, 

 of that class by their heteroclitical form. To the naked eye they seem 

 nothing more than two lobes united in the form of a horse-shoe, which en- 

 closes two others. By the aid of glasses, however, we discover that 



(1) The King-crab of our fishermen, or the Horse-shoe. Very common: 

 on the coast of New Jersey. 



