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argentea, Viola striata, and Cornus canadensis. —— 
Dr. T. S. Stevens exhibited a little garter-snake 
(Eutaenia sirtalis) preserved by nature in an interest- 
ingmanner. It had been taken from beneath a wheat- 
stack in its present condition, the body thrown in 
graceful coils and curves, the head erect, the whole 
appearing like a snake on the alert, yet dead, perfect- 
ly dry and mummy-like, and presenting only the 
slightest changes externally. According to Dr. Ste- 
vens, it has remained in this condition, without any 
special attention, for ten years. 
Academy of natural sciences, Philadelphia. 
March 4.— Professor Joseph Leidy stated that he 
had recently been supplied with specimens of a wheel- 
less rotifer, attributed to Apsilus, which had been 
found abundantly last autumn, in a pond at Fairmount 
Park, attached to Anacharis, and in the Schuylkill 
River, near by, attached to Potamogeton. They were 
recognized as Dictyophora, first described in 1857; and 
as aresult of the last examination, Professor Leidy 
was led to the opinion, that this form, the Apsilus 
lentiformis of Mecznichow, the Capelopagus lucine- 
dax of Forbes, and the Apsilus bipera recently de- 
scribed by Miss Foulke, are all the same species. 
In the recent specimens, he had recognized the lateral 
antennae ending in exceedingly delicate and motion- 
less cilia, as indicated by Mecznichow, and which pre- 
viously, from the wrinkled condition of the specimens 
detached from hard objects, had escaped his atten- 
tion. In all the forms described, the prehensile cup, 
in the same manner, is projected from, and with- 
drawn within, the mouth of a compressed oval or 
nearly spherical carapace, dotted with minute tuber- 
cles. This cup, substituting the usual rotary organs 
of rotifers, communicates with a capacious, variably 
sacculated, and dilatable stomach, followed by the 
ordinary gizzard with its mastax, and then a second 
sacculated stomach. ‘The size of the European forms 
is fully thrice that of the one now described. Miss 
S. G. Foulke described a species of ciliated infusorian 
of the genus Trachelius, found in the form of a white 
speck in water from the Schuylkill River. Rev. 
Dr. H. C. McCook, referring to the spinning-work of 
spiders, stated that the orb-weavers have, as a rule, 
but one egg-nest; but this, in the different species, 
varies widely in form, size, position, ete. There are, 
however, four species which make several cocoons in 
connection with their webs. The labyrinth spider, 
Epeira labyrinthica, weaves a web of right lines 
crossing at all angles above the orb-web. In the 
midst of these right lines the spider lives, almost 
always under a dried leaf. Under the leaf is a little 
white silk tent or belt-shaped nest connected with the 
web by a trap-line. Hanging above the tent are 
nearly always five cocoons, braced above and below 
by a strong silken line. They consist of a lower cup 
portion, covered by a sort of lid, and each contains 
about twenty eggs. The tailed spider, Cyrtophora 
caudata, generally makes five nests, containing in the 
aggregate a hundred or a hundred and twenty-five 
eggs. These are strung along the median line of the 
orb-web. They are at.first composed of a yellowish, 
SCIENCE. 
slightly viscid plush, and are afterwards covered with 
fragments of captured insects. This may be an in-. 
stance of protective mimicry, as the cocoons so Ccov- 
ered closely resemble the spider itself; or it may be 
due to the maternal impulse to protect the reposito- 
ries of the young as far as possible. Epeira basilica, 
which forms a beautiful dome-like web placed over a 
silken sheet, suspends its cocoons vertically in the 
centre of the snare. They consist of a dusky gray 
silken sac, within which is a hard ball like a cherry- 
stone. This ball is quite black, but proves, when 
placed under a microscope and illuminated, to be 
woven of a fine-textured yellow silk. It is filled with 
finely chopped silk, in which the young spiders are 
hatched. Uloborus riparia makes a horizontal web, 
the cocoons being strung horizontally from the cen- 
tre. They are double cones, covered with little pro- 
tective points. 
Mathematical section, philosophical society, Washington. 
Jan. 80.—Mr. G. K. Gilbert made a communica- 
tion on the Knight’s tour, on other fields than those 
of sixty-four squares. He showed that a complete 
tour was impossible if the number of squares was 
odd; that a tour having bilateral symmetry (latter 
half of the moves symmetrical with former half, with 
respect to a line through the centre of the field) was 
impossible if the number of squares was divisible by 
four, and hence altogether impossible on square fields ; 
that a tour having quadri-radial symmetry (divisible 
into four parts, which exactly repeat themselves when 
the board is turned through aright angle about the 
centre of figure) was impossible if the number of 
squares was divisible by eight; that the only sym- 
metry possible on the ordinary chess-board was there- 
fore bi-radial (of two parts that coincide when the ~ 
board is turned through two right angles). Upon a 
field of thirty-six squares, twenty tours with bi-radial 
symmetry are possible: of these, five have also quadri- 
radial symmetry. 
NOTES AND NEWS. 
THE following communication, kindly placed in our 
hands by the committee on invitations and receptions 
of the Philadelphia meeting of the American associa- 
tion, will interest the members of the association : — 
BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE, 
22 ALBEMARLE STREET, LONDON, W., 
Feb. 27, 1884. 
DEAR sir, — The resolution of the American as- 
sociation, inviting members of our association to Visit . 
Philadelphia and take part in its meeting, was read 
to our general committee by Principal Dawson, and 
was received with enthusiasm. No definite resolu- 
tion in reply was, however, proposed; because it was 
felt that the visit to Canada was only then assuming __ 
definiteness as to its outlines, and it was impossible ~ 
to say what arrangements might be made in that 
country. But the members of the association were 
fully sensible of the courtesy and kindness of their 
American brethren; and the enclosed resolution, — 
which was passed. by the council at their last meeting, 
