496 ZOOLOGY. 
than the penultimate), but well developed, single-rooted, circular, 
very obtusely conical. There is nothing to meet it above, since it 
sets entirely back of the upper series. On the other side of the 
under jaw there is a slight pit in the bone, corresponding to the 
situation of the extra molar, and showing an ineffectual nisus in 
the same direction. In all other respects the dentition is normal. 
To judge from a limited experience, this is an uncommon anomaly ; 
I have never before met with it in a feral animal. The prepara- 
tion (No. 2,728 of the writer's coll.) goes to the Smithsonian. 
—Exuiorr Coues, Fort Randall, Dakota. 
How ro Crean tHe Evprectetta.—This beautiful sponge is 
becoming a favorite, and deservedly, with lady collectors. Its 
marvellous delicacy and purity, after long exposure without a glass 
shade, becomes sadly injured by the adhering dust. I had a speci- 
men given me lately, which, from this cause had become so un- 
sightly as to be accounted worthless. I filled a deep jar with 
water, and stirred into it a good table spoonful of chloride of lime. 
An hour or so was then given for the lime to settle. After this, 
the specimen, held by a clean thread, was suspended in the fluid . 
for twelve hours or so. It was then taken out by the thread, and 
suspended a few hours in clean water. This entirely removed the 
chlorine. It was then suspended in the air to dry, after which 
it was of immaculate whiteness, and sparkled like the frosted 
snow.— S. L. 
Woovrrckers Tapping Sucar Trees.— Upon the Iowa Uni- 
versity campus we have a number of grand old aboriginal oaks, & 
favorite resort for redheaded woodpeckers (Melanerpes erythro- 
cephalus). Among the young and growing trees that have been 
transplanted upon the campus are some sugar maples (Acer saccha- 
rinum) the bodies of which are six or eight inches in diameter. 
Seeing the woodpeckers busily tapping upon them I examined the 
trunks and found them perfectly sound, but the birds had pierced 
many holes, of the usual size, through the bark and into the 
cambium layer, where they stopped. The sap was flowing freely 
from the holes, and, watching the movements of the birds after- 
ward upon the trees, I became convinced that they were sucking 
the sap and that they had pecked the holes for the purpose of 
obtaining it. This habit is probably not new to ornithologists, but 
I am not aware that it has before been noticed. C. A. WHITE. 
