424 
fucker of the mandibles, and which con- 
veys the food between them; two {mall 
articulated barbles, which, in the male, 
refembJe harpoons, and which induced 
Muller to think, though wrongly, that 
they were the fexual organs ; two branch-. 
ing antenne; five pair of feet, extremely 
complicated, and which produce a retro- 
grade current in the water behind them— 
a current which caufes the molecule, 
on which the infe& lives, to move towards 
the extremities of thofe fect, from whence 
they re-impel them towards the mouth, 
by a very fingular mechanifm ; the firft of 
thefe pair is the longeft, and is armed with 
two crotchets, or heoked claws, in the 
male; there is, laftly, a very mobile tail, 
terminated by two {pinous flat excrefcen- 
ces. 
Citizen Jurine does not confine himfelf 
to thefe extericr parts. As the infect is 
tranfparent, he has been able to defcribe 
the intericr. Near the inteftinal canal are 
two fpecies of coecum, which appear to 
fhed a diffulving liquor; the heart, fituated 
towards thé back, is contracted about 
z00 times in a minute. The ovaries, in 
number two, contain a greenifh matter, 
which they caule to pafs fucceffively into 
the matrix, where it is formed into diftin& 
eggs, which are hatched there. This 
matrix can contain, at once, 18 young 
ones. + 
Citizen Jurine enters with much detail 
into the hiftory of this infe&t. The male 
is fmaller, by half,.than the female. 
When about to copulate, he darts upon 
her, feizes her with the long fibres of his 
fore claws, clafps her with his harpoons, 
and draws his tail towards the fhell of the 
female,. who flies off, at firft, with rapi- 
dity ; but the male ftill adhering, fhe, at 
length, conforms her pofition to his. The 
copulation does net laft above an inftant. 
The eggs are nine or ten days hatching 
in winter, and two or three only in fum- 
mer. The young plex only differs from 
the adult, by more length in the poine 
which terminates their fhell.- Muller.has, 
improperly, made a {pecies cf them (dapb- 
nia longifpina.) In fammer thefe mo- 
nocles mew or calt their fkin, eight times 
in nineteen days; the ovaries only appear 
after the third time. In winter, there 
fometimes pats eight or ten days between 
two moultings. The fir laying of eggs 
produces four or five young ones; the 
. others goon augmenting to about eighteen. 
Their fecundity is fometimes fiopped by a 
fingular malady, the f{ymptom of which is 
a blackith fpot, fomewhat refembling a 
fadcle, placed on the back. Citizen Ju- 
\ 
Proceedings of Learned Sacieries. 
[Dec. 1, 
rine conceives this fpot to proceed from 
the difplacing of the matter of the eggs. 
Laftly, the moft fingolar faét of ail 
thofe difcovered by Citizen Jurine, is, that 
a female, which has received the male, 
tranfmits the impregnating influence to 
her female defcendants, fo that they all 
lay eggs, without being obliged to copu- 
late, to the fixth generation, after which 
they perifh in mewing. Another fpecies 
has carried this influence of one fingle co- 
pulation to the fifth generation: the ver- 
min‘ called vine-fretters (/es pucerons) 
have, as is well known, furnifhed fimilar 
obfervations to Bonnet. Thefe genera~ 
tions without copulation are lefs abund- 
ant, and fucceed each other lefs rapidly, 
than thofein which the males have borne. 
a part. 
BOTANY. 
Defcriptions of New Plants, or fuch as are 
little known, in the Gardexw of Citizex 
CEs, by Citizen VENTENAT, 
This work is one of the fineft which 
has appeared on the defcriptive part of 
botany, and it refle€ts equal credit on the 
two membets of the Clafs who have con- 
tributed to it: Citizen Cels, by his geal 
in procuring, from all parts of the world, 
the feeds and plants difcovered in them, 
and by Ins fkill in making them come to. 
maturity ; and Citizen Ventenat, for the 
elegance and accuracy of his defcriptions—- 
for the botanic erudition which he dif- 
plays—for the juftnefs with which he affi- 
milates the new genera and the new fpe- 
cies, lately difcovered, of thofe which 
were before arranged in fyftem; and, 
laftly, by the curious obfervations which 
he makes on their properties. The plates, 
engraved from the defigns of an artift, 
whom it is fuficient to name, Citizen Re- 
doute, defigner to the Ciafs, are fuch as 
may be expected from the fkilful engravers 
who have charge of them; that is to fay, 
that if forme works executed by the fame 
perfons be excepted, fuch as the Flora 
Atlantica of Citizen Desfontaines, no 
book 6f the kind prefents any fo highly 
finifhed. Four numbers have already ap- 
peared, containing each ten plants. 
Notice of the Hiftory of the Oaks of America. 
We owe the fame tribute of eulogium 
to the work of Citizen Micuaux, en the 
oaks of America. It is a faét,-fingular 
enough, that the oak genus, of which we 
have fo few {pecies in Europe, fhould be 
fo diverfified, under the fame latitude, in 
the new continent. The hiftory of thefe 
numerous {pecies is-fo much the more in- 
terefting, as they may be, doubtlefs, oe i 
; the. 
