210 MARINE INVERTEBRATES 



ward. It has a large, pentagonal, bright-scarlet disk, five to six inches 

 in diameter, with arms rather long a,nd pointed. The upper side is raised 

 and cushion-like, and is covered with blunt spines ; the margins have 

 larger spines of the same shape. The pedicellariae are sessile and so 

 long and large as to be easily seen with the naked eye. (Plate LII.) 



FAMILY PENTACEBOTIDJE 



GENUS Pentaceros 



P. ocddentalis. Pentagonal ; eight to twelve inches in diameter ; 

 ossicles a network of rod-like plates, with prominent spines at the points 

 of union ; body inflated in the center and running in wedge-like form 

 to the ends of the rather long and narrow arms ; the upper lines of 

 the ridges have spines more prominent than those on the rest of the 

 body ; the spines of the larger specimens are more like large warts or 

 small hemispheres. Found on the Lower California coast. 



J*. reticularis. This starfish is the largest species on our coasts. It 

 is common in southern Florida close to the shore. The body is three 

 to four inches thick, flat on the oral surface, but raised on the upper 

 side, and tapers down in wedge-like form to the points of the short arms. 

 The prominent blunt spines which cover its surface are arranged in a 

 somewhat regular net-like order, and the sharp-edged margins have an 

 even row of larger spines of the same form. The madreporic plate is 

 nearly in the center of the disk, and is quite conspicuous, being bordered 

 with a circle of small spines. Its color is dull yellow, and its size often 

 a foot or more in diameter. It is the large starfish so often seen in curi- 

 osity-shops. (Plate LII.) 



GENUS Nidorella 



N. armata. This very curious pentagonal species, found on the 

 California coast, is five to six inches in diameter and red in color. The 

 upper surface is raised and covered with thick, pointed spines one half of an 

 inch to one inch long, arranged in lines, but not crowded. The ossicles 

 on the margins are large ; some of them are hemispherical and bear 

 large spines. Smaller spines border the under edge of the margins. 

 (Plate LIII.) 



FAMILY ASTEKIHIDJE 



The starfishes of this family are pentagonal, with a large body 

 and short arms. The disk is more or less elevated in the center, 

 and the. edges are sharp. There are two rows of ambulacra. The 

 ossicles are notched and overlapping. The family is confined to 

 temperate and tropical waters. 



GENUS Aster ina 



A. folium. Small, pentagonal, swollen (gibbous). Found on the 

 Florida coast. 



