REPORT OF STATE BIOLOGIST. 6 



which contains the alimentary canal, liver, generative pro- 

 ducts, etc. It is by means of this "foot" that the clam is 

 enabled to get out of the reach of the clam digger, if the latter 

 does not work quickly, for it stretches it down through the soft 

 yielding sand as far as it will go. then the lower end is ex- 

 panded, forming a temporary suction, and the retractor mus- 

 cles of the foot are then contracted. Ordinarily, the effect of 

 this would be to draw back the foot, but, the lower end of 

 this organ being at this time expanded or curved, the body of 

 the clam is drawn down to the improvised anchor, and the 

 process is then repeated. This, with minor modifications, is 

 the method of locomotion with most of the clams. 



At the end of the clam opposite the. foot the "siphon," 

 wrongly called the "neck," protrudes. This is a curious 

 organ and lias to do with the respiration and feeding of the 

 creature. Two tubes traverse this siphon longitudinally, one 

 opening into the space just above the gills, the other, the one 

 nearer the ventral or free edge of the shell, opening into the 

 general space between the valves of the shell. In this space, 

 on each side of the visceral mass are two gills, four in all, 

 which serve as organs of respiration ; and covering and pro- 

 becting both visceral mass and gills is a thin layer of tissue 

 known as the "mantle." This mantle lies next the nacreous 

 inner layer of the shell which it has helped to form by its 

 secretions. When the clam is in the sand and covered with 

 water the siphon is stretched until its end is above the surface 

 of the sand. Water is drawn in the lower opening and passes 

 over and through the gills, the minute particles of food con- 

 tained therein being carried to the mouth which is at the 

 lower or anterior pari of the animal ; the water which has 

 passed through the gills, flows back and out through the other 

 tube, the exhalent tube of the siphon. The smooth epidermis 

 covering the outer surface of the shell is of a brownish color 

 and glistens as though it were varnished. There are evidently 

 nerve endings at the distal end of the siphon which are sensi- 

 tive to light and shadow, though this has not been definitely 

 proven for this species. The sexes are distinct, as will be 

 shown later. This is placed beyond all question, even if it 

 had not been previously known, by these recent studies. Yet 

 there are those in the State who claim that these animals are 

 hermaphroditic. Familiarity with the use of the microscope 

 and a knowledge of the anatomy of the creature would soon 

 dispel this erroneous conception. 



