OF MASSACHUSETTS. 65 



against the wire. To observe their recovery from injury, scallops were 

 treated in a variety of ways: (1) four scallops were unhinged by break- 

 ing the ligament; in three days' time three were dead, one was alive; 

 (2) small holes were bored in shells of three scallops: all were dead in 

 three days; (3) five with adductor muscle badly strained: in three days 

 two were dead, three alive; (4) three with valves cracked lengthwise: 

 in three days one was alive, two were dead; (5) one with valve cracked 

 along byssal groove: alive two weeks later but shell not mended; (6) 

 three with small piece cut out of mantle edge; in three days two were 

 alive, one was dead. The result of these mutilations shows that the 

 scallop, although not as hardy as the clam or quahaug, is capable of 

 repairing minor injuries inflicted by enemies, and only succumbs to the 

 more severe hurts. 



Feeding Habits. 



The feeding habits of the scallop are similar in many respects to those 

 of the other shellfish, as all lamellibranchs obtain their food by means 

 of the gills, which act as filters or strainers. The clam and quahaug lie 

 beneath the surface of the soil and reach the water by a fleshy extension 

 of the mantle, known as the siphon. The scallop has no siphon and its 

 method of life is such that it does not need an organ of this nature. 

 When in a natural position for feeding, the animal rests on the bottom 

 on its right valve, the shell gaping open at an angle of about 20°. 

 Closely lining the inside of the two valves is a thin fleshy substance, the 

 mantle, described in chapter II. When extended, the edge, lined with 

 papillose tentacles and brightly colored eyes, passes beyond the shell, 

 while another portion, consisting of a perpendicular ilap, surmounted 

 with a row of closely set guard tentacles, acts as a curtain to nearly 

 close the intervening space between the open valves. Instead of the 

 specialized siphon of the clam, which is in reality only a part of the 

 mantle, the scallop makes use of the entire ventral area of this fold to 

 take in its food, with the result that a continual stream is passing in 

 through the mantle and going out at a definite locality in the posterior 

 side of the shell. This portion of the mantle is destitute of guard 

 tentacles, and, when the walls are closed together, forms a pseudo- 

 siphon. 



The food of the animal, as more fully described in the report on the 

 food of the lamellibranchiate mollusks, consists largely of certain micro- 

 scopic plants, called diatoms. These tiny forms are extremely varied in 

 size and shape. They are easily recognized by their silicious cases and 

 beautiful markings, which have won for them the name of " the jewels 

 of the plant world." They are found in the water everywhere in more 

 or less abundance, and are filtered out by the scallop from the water 

 which bathes its gills. 



The four gills, which were described in chapter II., in addition to 

 aeration of the blood possess the important function of straining food 



