CAKE-URCHINS 



225 



the cone in straight lines, and around the base is a depressed area which 

 emphasizes a thick border which extends around the scalloped margin. 

 The color is light yellowish-brown. (Plate LVIII.) 



GENUS Echinanthus 



E. rosaceus. This is a large species, cblong in shape, about four to 

 five inches across and much rounded on top, the body being about two 

 inches thick. The ambulacral zones 

 are depressed, leaving prominent 

 elevations which make a very con- 

 spicuous figure on the top. The color 

 is light chocolate-brown. Found 

 close to the shore off the coasts of 

 Florida, South Carolina, and the 

 West Indies. 



FAMILY SCTTTELLIDJE 

 GENUS lEchinarachniiis 



THE SAND-DOLLARS 



E. parma. This species, the shells 

 of which are very common objects 

 on sand-beaches from New Jersey 

 northward, is generally known as the 

 sand-dollar. The animals have flat circular disks about three inches in 

 diameter. The ambulacral zones, in five petal-like lines, form a distinct 

 figure on the upper surface. The mouth is in the center of the ventral 

 surface, and the excretory opening is on the edge of the disk. In life 

 they are covered with short, fine, sUky spines, which seem like hair, and 

 are purplish-brown in color, but turn green when taken from the water. 

 The sand-dollars are exceedingly abundant off Nantucket Shoals, where 

 the bottom seems paved with them. They are eaten in great numbers 

 by flounders, cod, and haddock. When put in alcohol they stain it a 

 dark color. Fishermen prepare an indelible ink by grinding to powder 

 these ardmals and mixing it with some liquid. This species is also found 

 on the northern Pacific coast. 



E. excentricus. This is the common sand-dollar of the Pacific 

 coast. The disk, instead of being circular as in E. parma, is somewhat 

 straight across the posterior end, and the posterior ambulacral zones are 

 shorter than the other three. The upper side of the disk is raised, form- 

 ing a cone-like elevation, the apex being the center of the figure. 



GENUS Mellita 



M. testudinata. The disk is rounded in front and straight in the 



back. Four long, narrow lunales, or cuts, occur on the sides in line 



with the ambulacral, petal-shaped zones, but do not extend quite to the 



edge of the disk ; and a wide lunale occurs in the interambulacral space 



15 



Echinarachnius parma, the sand-dollar. Much 

 smaller than natural size. 



