ECHIN1DEA. C73 



by diving. The natives also fish the Uche-de-mer on rocky co- 

 ral bottom by the light of the moon or of torches, for the animals 

 keep themselves drawn up in holes by day, and come forth by 

 night to feed, when they may be taken in great numbers. The 

 motions of the animal resemble those of a caterpillar, and it 

 feeds by suction, drawing in with its food much fine coral and 

 some small shells. 



The prepared article finds a ready sale in the China market, 

 where it is used as an ingredient in soups. When brought on 

 shore, the animals are placed in bins where they remain the next 

 day ; the entrails are then removed ; the larger kinds are cut along 

 the under part for three or four inches to make them dry more 

 rapidly ; then thrown into pots of the form of sugar boilers, con- 

 taining from one hundred to one hundred and fifty gallons, and 

 boiled fifteen or twenty minutes, after which they are thoroughly 

 dried in a large building. This process makes the slug lose 

 two-thirds of its weight and bulk. When cured it resembles 

 smoked sausage. The biche-de-mer is sometimes taken to Can- 

 ton, but more usually to Manilla, whence it is shipped to China." 



Sometimes it is as much as two feet in length, and from seven 

 to eight inches in circumference; but a span long, and two or 

 three inches in circumference is the ordinary size. 



SECOND ORDER. ECHINIDEA, (Gr.'sxivog, echinos, a sea-urchin ; 

 eldog, eidos, form.) SEA- URCHINS OR SEA- EGGS. 



These furnish complete examples of the type of radiated ani- 

 mals. Their hard covering and habits of living in the sand have 

 preserved them in many rocky strata, so that in their fossil as 

 well as living forms, they are objects of interest to the naturalist. 

 Their usually oval or circular form has suggested for them the 

 name of Sea-eggs. Their more or less rounded form, without 

 any arms, distinguishes them from other Echinoderms. Within 

 their integument calcareous matter is deposited, forming a series 

 of regular plates, studded with tubercles which are jointed with 

 spines varying in form and size, according to the genus to which 

 they belong. These spines " have a beautiful microscopic struc- 

 ture, being composed of cells which are arranged around a com- 

 mon center, almost in the same manner as the zones of wood in 

 a tree." The plates run in vertical rows or avenues, twenty in 

 number, two of which are wide and two narrow, alternately, the 

 tubercles of the wide pair supporting the larger spines ; the nar- 

 row ones have vertical rows of minute perforations, which allow 

 the passage of the sucker-like feet, that in addition to the spines, 



