REPORT OF COMMISSIONERS OF INLAND FISHERIES. 25 
after it was caught, 7.¢., on June 14. It is drawn to the same 
scale of magnification as those in figure 1. The shape of the shell 
has been greatly changed, and the clam is more than twice the 
length, and many times the bulk, of even the largest specimen 
when first caught. The siphon (snout), gills, liver, stomach, and 
heart, and the relatively large foot have been developed, the inter- 
nal organs showing plainly through the transparent shell. Figure 
3 represents the same individual, drawn with the camera, to the 
same scale, ten days later, on June 24. The body is now still 
further elongated, the gill-plates are considerably more numerous, 
the foot is, perhaps, somewhat larger in proportion, and a peculiar 
sense organ, the so-called ear, is plainly visible within the substance 
of the foot. The lines of growth, which can be easily made out upon 
the shells themselves, show the changes in shape which have taken 
place during the process of growth. Although the rate of growth 
in this specimen is seen to have been quite rapid—trom the size of 
one of those in Fig. 1 to that in Fig. 3 in less than three weeks— 
it was doubtless much less rapid than it would have been under 
natural conditions; for this specimen was kept in a dish, the water 
being changed only a few times, so that the supply of food, which 
consists of microscopic organisms, was very meagre as compared 
with that in the tide-water. 
Among the clams caught in the skim-net there were usually 
many in which the foot and siphons were already developed. 
Such specimens, when watched under the microscope, would 
crawl about by means of the foot instead of swimming’; yet they 
must have been able to swim, since they were taken near the sur- 
face of the water. I am not certain whether the swimming-organ 
was still capable of being used, or whether they swim with the 
foot. The latter method I would have thought almost impossible 
had I not seen it in use by razor clams which were many times 
larger. On the evening of July 20 a large number of razor clams, 
some of the latter measuring seven millimetres (more than a 
quarter of an inch), were taken in the tow-net. The shells were 
well-formed and hard, but the animal swam rapidly about by 
4 
