silia (non stipitatus), perfecte cylindricus, apice rotunda- 
tus, rufo-brunneus;: spathae parte inferiore breviter adna- 
tus, circiter 5.5 cm. longus, 1 em. in diametro, a medio 
fertiles. Flores quattuor-tepal, virides. Ovaril obovoidei, 
loculi quattuor-ovulati. Baccae seminaque adhue ignoti. 
Urospatha antisylleptica differs from 7. decipiens pri- 
marily in being much larger and in having the sinus be- 
tween the median and lateral lobes of the leaf at least 
twice as long. From Uvrospatha Hostmanu, the new spe- 
cies may be distinguished by its larger size, by its verru- 
culose (not glabrous) petioles and by its having the base 
of the spathe only very shortly adnate to the spadix. 
The bright blood-red or scarlet callus at the base of the 
leaf blade or apex of the petiole in Uvrospatha antisyllep- 
fica may beadistinguishing feature from all other species, 
for | have seen no reference to such a color in the litera- 
ture nor have I noticed it in several other species of this 
genus Which [ have had occasion to study and collect in 
the field. 
Urospatha antisylleptica was pointed out independently 
by two Barasana Indians, who inhabit the upper course 
of the Rio Piraparana and its affuents, as the source of 
an oral contraceptive which is in common use in the 
tribe. They report that the unripened spadix is dried and 
pulverized and that, in order to prevent conception, the 
resulting brown powder is added to food given to any 
woman. My stay in the Rio Piraparand was not long 
enough to permit me to check these statements thor- 
oughly or to see the plant used. Since the two sources of 
this information were independent of each other and since 
species of the -fraceae are said to be similarly used in 
other parts of the Vaupés and elsewhere, Lam inclined to 
give credence to the reports. The specific name antisyl- 
leptica (from the Greek meaning “‘against pregnancy’) 
has been chosen to call attention to this unusual use of 
the plant. 
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