REPORT OF COMMISSIONERS OF INLAND FISHERIES. 39 
ted in a dish of water. Seen from the left side: f, foot retracted ; 
l, liver; h, heart; g, gills; s, siphon or “snout.” Arrows indi- 
ho 
cate incurrent and excurrent openings. 
3. The same individual as Fig. 2, drawn to the same scale of 
magnification, ten days later, viz.: on June 24; e, sense organ 
(ear?). Other letters the same as Fig. 2. 
4. Freehand sketch of clam larva seen through the microscope 
with swimming-organ (velum) expanded. Around the edge of 
the velum is the fringe of minute lashes (cilia) whose movements 
propel the animal. The arrow shows the direction of the current 
of water created by the rapid stroke of the cilia. The direction 
of the current is easily ascertained by observing the movement of 
the small particles contained in the water. 
5. Sketch of a clam just set, as seen under the microscope. 
The large foot and the siphon are shown distended. The dotted 
line indicates the position of the foot when retracted within the 
shell. The incurrent and excurrent tubes of the siphon are, at 
this stage, nearly separate. 
6. Specimens selected to represent the average size of the 
clams in a marked area on the shore of Cornelius Island, Wick- 
ford, R. L, on July 7, 1899. The largest specimens are, prob- 
ably, about six weeks old. Photograph life-size. 
fond 
7. Specimens selected to represent the average size of the 
clams in a marked area on the shore of Cornelius Island, Wick- 
ford, R. L., on July 14,1899. The largest specimens are, probably, 
about seven weeks old. Photograph life-size. 
8. Specimens selected to represent the average size of the 
clams in a marked area on the shore of Cornelius Island, Wick- 
ford, R. L., on July 21,1899. The largest specimens are, probably, 
about eight weeks old. Photograph life-size. 
9. Specimens selected to represent the average size of the 
clams in a marked area on the shore of Cornelius Island, Wick- 
