THE CLAM FISHERIES. 



613 



introduced clams in the following figures I am not informed ; but his totals reported from Cali- 

 fornia of edible shell-fish other than oysters, is as follows: 



Statistics of clams gathered in California in 1880. 



() THE RAZOR FISH. 

 19. NATURAL HISTORY AND COMMERCIAL IMPORTANCE. 



Another bivalved mollusk to be noticed among our edible shell-fish is the razor-clam (Ensa- 

 tella americana), which is a common inhabitant of sand-flats and sand-bars, where the water is pnre, 

 generally living near low-water mark or below, but sometimes found considerably above low- 

 water mark. "This curious mollusk, r writes Professor A. E. Verrill, in one of the pleasantest of 

 his many pages concerning New England's invertebrates, "constructs a deep, nearly round, some- 

 what permanent burrow, which descends nearly perpendicularly into the sand to the depth of 2 or 

 3 feet. These holes can generally be recognized, by their large size and somewhat elliptical form, 

 when the tide is out. Sometimes they are very abundant in certain spots and not found elsewhere 

 in the neighborhood. They sometimes come to the top of the burrow, when left by the tide, and 

 project an inch or two of the end of the shell above the surface of the sand ; at such times, if 

 cautiously approached, many can easily be secured by pulling them out with a sudden jerk, but 

 if the sand be jarred the whole colony will usually take the alarm and instantly disappear. 

 When thus warned it is generally useless to attempt to dig them out, for they quickly descend 

 beyond the reach of the spade. They will often hold themselves so firmly in their holes by means of 

 the expanded end of the long muscular foot, that the body may be drawn entirely out of the shell 

 before they will let go. When not visible at the orifice they can often be secured by cutting off 

 their retreat with a sudden oblique thrust of the spade below them. They are obliged to come up 

 to the upper part of the burrow on account of the shortness of their siphons or breathing-tubes, 

 which can be protruded only about an inch in specimens of the ordinary size, and, as they depend 

 upon one of these to bring them both food and oxygen, and on the other (dorsal) one to carry off 

 the waste water and excretions, it is essential for their happiness that the orifices of these tubes 

 should be at or near the opening of the burrow most of the time. In this respect the common 

 'long clam' (Mya arenaria) and many others that have very long and extensile tubes have a great 

 advantage. But the 'razor-shell' makes up for this disadvantage by its much greater activity 

 Its foot or locomoitve organ is long and very muscular, and projects directly forward from the 

 anterior end of the shell ; at the end it is obliquely beveled and pointed, and it is capable of being 

 expanded at the end into a large bulb, or even into a broad disk, when it wishes to hold itself 

 firmly and securely in its burrow. In excavating its burrows it contracts the end of the foot to 

 a point and then thrusts it beneath the surface of the sand ; then, by forcing water into the ter- 

 minal portion, it expands it into a swollen, bulbous form, and thus crowds the sand aside and 

 enlarges the burrow ; then, by using the bulb as a hold fast, the shell can be drawn forward by 

 the contraction of the foot ; the latter is then contracted into a pointed form and the same opera- 

 tions are repeated. The burrow thus started soon becomes deep enough so that the shell will 



