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. 



Polynoe squamata. 



GENUS Polynoe 



The species of Polynoe 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 

 papillae at the top. They are sluggish in movement 

 and are found under stones and in the ere vices 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 Polynoe 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 ; 

 length one and a quarter inches, breadth about one 

 quarter of an inch. 



GENUS Harmothoe 



H. imbricata. Sixteen pairs of smooth scales ; variable in color ; 

 usually gray, speckled, or striped. 



GENUS Aphrodite 



A. aculeata. This polychsete, sometimes called the sea-mouse, is one 

 of the most beautiful of worms. It is brightly iridescent in color, from 

 its setse, which form a fur-like coating over the dorsal surface. It has 

 fifteen pairs of scales, but they are hidden by the numerous setae. 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 sis 

 inches long. It is broadest iu the middle and tapers to a point. They 

 live in mud below tide-mark, and may be found washed upon the beach 

 after storms* 



