174 MARINE INVERTEBRATES 
podia, and generally on alternate segments and in a double row 
down the back. The elytra are the breathing-organs, and, although 
of a horny texture, are richly supplied with nerves. The worms 
are short and have a large protrusible pharynx armed with a 
double pair of horny jaws. 
Genus Polynoé 
The species of Polynoé are determined by the 
number of scales they bear. They have a flattened 
short body with nearly parallel sides. The bristles 
are of a bright golden color. The proboscis is large 
and has four powerful jaws at the end and a circle of 
papille at the top. They are sluggish in movement 
andarefound understonesandin the crevices of rocks. 
When disturbed they roll themselves into a ball. 
P. squamata. Twelve pairs of rough scales; color 
sandy-brown, speckled; one inch to one and a half 
inches long; the broad, oval scales overlap and entirely 
cover the body and head. Some Polynoé when disturbed 
throw off every scale. Very common north of Cape Cod. 
P. sublevis. Twelve pairs of smooth scales; usually 
grayish-brown in color, speckled with dark spots; iri- 
\ descent; last pair of scales more slender than the others ; 
Polynoé squamate. length one and a quarter inches, breadth about one 
quarter of aninch. 
Genus Harmothoé 
H. imbricata. Sixteen pairs of smooth scales; variable in color; 
usually gray, speckled, or striped. 
Genus Aphrodite 
A. aculeata. This polychete, sometimes called the sea-mouse, is one 
of the most beautiful of worms. It is brightly iridescent in color, from 
its sete, which form a fur-like coating over the dorsal surface. It has 
fifteen pairs of scales, but they are hidden by the numerous seta. These 
bristles cover its sides and back. Some are coarse and nearly an inch 
long, with sharp points, and are barbed near the ends. They curve 
over the back like the quills of a porcupine. The body is three to six 
inches long. It is broadest in the middle and tapers to a point. They 
live in mud below tide-mark, and may be found washed upon the beach 
after storms. 
