152 SEA-SHORE LIFE 



however, not derived from the plumed gills of other snails, but are 

 a new formation found only among the Nudihranchiata. The back 

 is apt to be covered with finger-shaped processes which proba- 

 bly function in respiration, and the head is provided with eyes 

 and tentacles. 



These most interesting little snails match their surroundings 

 to a wonderful degree of perfection, their ragged- looking backs and 

 mottled color giving the impression of a piece of torn seaweed. 

 They crawl upon sea weeds or stones, but can also swim foot up- 

 wards along the surface of the sea. 



jEoUs papillosa is the commonest species under stones or upon 

 sea weeds in shallow water off our north Atlantic coast, and the 

 shores of Europe. It grows to be about three inches long, but spe- 

 cimens over an inch in length are rare. It is very variable in 

 color, being fawn, gray, or yellowish sprinkled with large dots of 

 white, olive, brown, purple or yellow. The body is square in front 

 but tapers to a point behind. There are two pairs of tentacles 

 upon the head, and numerous rows of papillae, down both sides, the 

 middle of the back being bare. The eggs are laid in a white gela- 

 tinous cord, festooned and coiled in a spiral, and deposited upon 

 stones. A good figure and description of this creature is given by 

 Gould and Binney. "Invertebrates of Massachusetts," p. 238. 

 Plate XVIII. Figs. 257-263. Curiously enough the skin of this 

 creature is provided with stinging thread-cells similar to those of 

 jelly-fishes and sea anemones. It is probable, however, that these 

 thread cells may have been obtained from sea anemones upon which 

 the mollusk has fed. 



AncAiJa sulphiirea is a pale yellow species commonly found on 

 rocky bottoms off the New England coast north of Cape Cod ; being 

 very abundant in water about 200 feet deep. 



THE SQUID, OCTOPUS AND NAUTILUS. 



Cephalopoda. 



These are the most highly developed mollusks, and when one 

 observes their remarkably rapid movements, their acute senses, and 

 the complexity of tlieir entire organization, it is difficult to convince 

 one's self that their nearest living relatives are snails and clams. 



They are all carniverous, and prey iipon fishes, crustacea and 

 other mollusks which they capture by darting backward, seizing 



