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POPULAR SCIENCE REVIEW. 
IUestelia, in which the elongated peridium separates in 
threads which are either united at their apices or free. 
Peridermium, in which the elongated peridium ruptures 
irregularly. 
tEcidium, in which the peridium opens by reflexed teeth. 
Endophyllum, in which the peridium is immersed in the 
substance of the leaf. 
The second group contains two allied genera, i.e. : — 
Ustilago, in which the simple spores are produced as 
closely packed cells, and ultimately break up into a 
powdery mass. 
Tilletia, in which the reticulated spores spring from 
delicate branched threads. 
The members of the first group are associated together in 
one natural order termed jEcidiacei. Those of the second 
group form a portion of another natural order called Pucciniei , 
to which we shall have occasion to return in the next number. 
TILLETIA. Tulasne. 
Spores sphserical, reticulated, proceeding from delicate branched threads. 
Tilletia caries. Tul. (Bunt.) In wheat-grains. Autumn. Common. 
Plate III. — Fig. 1. Infected grain. — 2. Section of same. — 3. Spores 
magnified 320 diameters. — 4. Spores germinating, magnified 460 
diameters. — 5. Ditto, producing elongated spores. — 6. Conjugating 
spores. — 7. Elongating spores producing fruit of the third order. — 
8. Spore of third order germinating. 
TJSTILAGO. Link. 
Plant deeply seated. Spores simple, springing from delicate threads, or 
in closely packed cells, breaking up into a powdery mass. 
Ustilago Segetum. Ditm. (Corn smut.) On ears of corn and grass. 
Autumn. Very common. 
Fig. 22. Ear of smutted barley. — 23. Spores magnified 460 diameters. 
Ustilago urceolorum. Tul. (Sedge smut.) On the seeds of Carices. 
Autumn. Not uncommon. 
Fig. 19. Car ex recurva infected with smut. — 20. Smutted fruit. — 
21. Spores magnified 460 diameters. 
Ustilago longissima. Tul. (Elongated smut.) On leaves of Poa aquatica. 
Summer. Common. 
Fig. 26. Portion of infected leaf. — 27. Spore-spot magnified 60 
diameters. — 28. Spores magnified 460 diameters. 
Ustilago olivacea. Tul. (Olive smut). On Carex riparia. Not common. 
Ustilago hypodytes. Fr. (Grass-culm smut.) On culms of grass. Sum- 
mer. Sometimes not uncommon. 
Fig. 9. Infected stem of grass. — 10. Spores magnified 460 diameters. 
