220 College of Forestry 
clams, the young glochidia are discharged into the water and 
fall to the bottom where they le with their two shell valves 
widely open. Unless the proper host, which is nearly always 
a fish, comes along, they die. The next stage is passed as a 
parasite on some part — gills, fin or tail — of a fish. On their 
host they become encysted by an outgrowth of the skin of the 
fish which entirely covers the mussel embryo. After the 
lapse of a certain time (varying from 9 to 74 days in dif- 
ferent species) the embryo, having completed its transforma- 
tion, breaks the cyst and falls to the bottom a perfect young 
mussel though still very small. There are therefore four dis- 
tinct stages in the growth of a mussel: 1, fertilized egg; 2, 
elochidium in marsupium of clam; 3, parasitic stage encysted 
in fish or a Salamander; 4, post-glochidian development with 
fully formed shell. Subsequent growth is principally in size. 
(Lefevre and Curtis, 1910, b; Howard, 1914.) 
A single species, Strophitus edentulus, is known to develop 
without parasitism (Lefevre, 1911, p. 863; 1912, p. 171), 
elochidial development taking place in a cord in the gill which 
forms a sort of placenta or nutritive body. Both Strophitus 
edentulus and S. undulatus live in Oneida Lake or its 
tributary creeks. 
Unless the young mussel falls in a favorable locality on the 
bottom of the lake or str eam, it will not long survive. Young 
mussels less than 20-25 millimeters in size are seldom 
observed. Those described by Isely (1911) were found 
attached to rocks and pebbles by a byssus or thread. They 
were from 2.9 to 22.5 millimeters in length. The collec 
tions from Oneida Lake contained a few young mussels from 
like situations, as noted below: 
Anodonta cataracta, 9 mill. long. Sandy and bouldery bottom, 2 feet 
water (station XXI, 3, B. field No. 247). 
Alasmidonta undulata, 6 mill. long. Debris on sandy bottom, 20 in. 
water (station XXXI, 1, C. field No. 217). 
The almost universal habitat for mussels, a sandy, stony 
or bouldery shore, is good evidence that these places are the 
best adapted to the needs of the young mussels, and here they 
have remained and formed the mussel beds, where the 
environment provided the optimum conditions for successful 
