was always a good one for shells and other animals which the tide 

 had washed in. 



At one place we came to an elevated bank, which was solid with 

 black edible mussels, My til us edulis. There must have been literally 

 millions of shells attached to the bank and to each other, by their byssus 

 of little silken threads. Among the mussels we found periwinkles, 

 bubble shells, slipper shells, and 

 a host of others. Not the least 

 interesting inhabitants of this mus- 

 sel bank were the fiddler crabs, 

 which scampered oft 1 in every direc- 

 tion as we approached, holding 

 their one enormous claw ready for 

 battle. They soon disappeared in 

 their holes, their claw and big 

 pincer being visible just below the 



edge of the hole. The black mussel, Mytilus edulis, showing 



Rpfnvnino- to nnr pamnino-- byssus, by which it attaches the shell to some 

 ne m & object. (Binney's Gould.) 



ground, we found awaiting us 



a good dinner consisting of baked clams, bread and butter, and a gen- 

 erous slice of apple pie for each one. After dinner, Professor Parker 

 proceeded to give us a lecture on clams, and we willingly gave him our 

 closest attention. 



We were first told to examine the outside of the shell, and note the 

 brown, horny covering called the epidermis, which protects the limy 

 shell from injury by any carbonic acid which may be in the water. 

 As in the fresh-water clams, the soft -shelled clam has a rounded 

 anterior end and a wedge-shaped posterior end; a sharp ventral mar- 

 gin and a rounded dorsal margin, with the two beaks, or umbones, 

 placed a little in front of the center of the shell. The two valves 

 are alike, and the animal is therefore bilaterally symmetrical. It was 

 noted that the anterior end closed tightly, while the posterior end 

 opened, or gaped, to allow the siphons to be extended. 



Removing one of the animals from the shell, Professor Parker pointed 

 out its different parts, and their relation to the animal. In the right 

 valve we noticed the large scars of the adductor muscles at either end 

 of the shell, and the deep pallial line connecting them and showing 

 where the mantle of the animal was attached. Our attention was 

 called to the fact that this line was not straight, as is the case with 

 the fresh-water clam, but was curved, and had a bay, or sinus, at the 

 posterior part, called the pallial sinus. This showed that the animal 



63 



