332 THE AMERICAN NATURALIST. |. (Vor. XXXIX. 
during the first week in September. In each place the genera- 
tive season probably ends a little before the water reaches its 
maximum heat, which occurs at Eastport in September, at Bos- 
ton in August. Thus all of a lot of specimens from Nahant in 
the middle of August had the generative glands empty and the 
same was true of a considerable part of those gathered at East- 
port during the first few days of September. The eggs, which 
are about + mm. in diameter are not dropped separately, as is 
said to be the case in Patella, but are imbedded in a layer of 
very thin mucus in which they lie one layer deep and at regular 
distances apart. The mucus is secreted not by a special gland 
but by the sole of the foot. 
Fertilization is usually described as external. The only excep- 
tion that I have been able to find to this statement is that of 
Fischer, who in 1863, asserted that he had found the ovaries of 
Patella filled with embryos already provided with the shell. Dr. 
Dall kindly informs me that he was following this authority when 
in 1879 he stated that the fertilization in Docoglossa is internal. 
His statement in turn seems to have been the authority for that 
made by Tryon in his Manual. While I am not prepared to 
assert that fertilization is internal I wish to record the following 
observation, which certainly points in that direction. About 
nightfall a male was observed caressing a female. Both shells 
were raised, that of the male overlapping the female and the 
heads were placed side by side, the male stroking the female 
with his tentacles. After a few passes he would turn as if he 
were going to leave her and then come back. The proceeding 
lasted for about half an hour, the female remaining quiescent 
with tentacles folded about her head. At the end of this time 
she moved forward, pressed the left side of the neck against the 
corresponding region in the male so that the openings of the 
two nuchal cavities were brought close together, and after 
remaining a moment or two in this position turned and walked 
away pushing with some difficulty between two other limpets 
neither of which paid her any other attention than a momentary 
touching with the tentacles. The nephridial papilla through 
which the generative products are extruded lies not on the left 
but on the right side of the nuchal cavity, but the ciliary current 
