210 MARINE INVERTEBRATES 
ward. It has a large, pentagonal, bright-scarlet disk, five to six inches 
in diameter, with arms rather long and 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 pedicellariz are sessile and so 
long and large as to be easily seen with the naked eye. (Plate LIT.) 
FAMILY PENTACEROTIDE 
Genus Pentaceros 
P. occidentalis. 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. 
P. 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 israised 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 LITI.) 
FAMILY ASTERINIDE 
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 Asterina 
A. folium. Small, pentagonal, swollen (gibbous). Found on the 
Florida coast. 
