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TRANS. ST. LOUIS ACAD. SCIENCE. 
3 1 
in size in the same sporangium ; large and small ones are indiscriminately 
mixed; and they are also remarkably variable in their sculpture, showing 
distinct or confluent vermiculate tubercles, or a nearly smooth surface; 
the dividing ridges or commissures are very prominent and smooth. The 
leaf-bases of the typical form of this species are black and shining, and 
justify the name given by that zealous botanist, Jacques Gay, who in his 
75th year was still anxious and able to climb the high mountains in the 
centre of France, to study in their lakes the two European species which 
had just then become prominent through the labors of his friend Durieu 
de Maisonneuve, and who left us such a vivid description of his hardships, 
excitements and pleasures on that trip (Bull. S. B. F. vols. 8 & 9) ; death 
prevented him from publishing it, but his name remains connected with 
it. Now and then a paler specimen is seen, and the Texan form is always 
pale, and distinguished also by its broader velum. 
13. I. Butleri, Engelm. Dioecious, smaller than the last, with a 
subglobose trunk and thinner and more rigid bright green leaves, 8 to 12 
in number and 3 to 7 inches long; sporangium usually oblong, spotted, 
without any or with a very narrow velum; ligula subulate from a trian¬ 
gular base ; macrospores larger than in last, 0.50 to 0.63 mm. in diameter, 
similarly marked with knobs or warts, distinct or sometimes confluent; 
microspores Q.028 to 0.034 mm. long, dark brown, papillose. — Bot. Ga¬ 
zette, 1878, if. 1. 
Var. immaculata. Larger, leaves sometimes as many as 60, 6 to 9 
inches long; sporangium without spots ; macrospores rather smaller, 0.40 
to 0.56 mm. in diam.; microspores 0.029 to 0.031 mm. long, 'spinulose. 
In the saline flats (called alkali flats, but impregnated with sulphates) 
of the Indian Territory, near Limestone Gap, between Arkansas and Red 
rivers, associated with the few coarse plants which can live in those local¬ 
ities overflowed in winter and spring, and baked hard in summer and, 
lautumn* such as Iva angustifolia , Ambrosia fisilostachya , Arenaria 
Pitcheri, and with Isoetes melanofioda, but in rather drier localities than 
this; maturing in May and June, O. D. Butler. The variety near Nash¬ 
ville, Tenn., in cedar barrens, in damp places on the limestone flats*, with 
Leavemvorthia $ Talinum , Sedum fiulchellum, Schoenolirion , several Junci, 
etc., A. Gattinger. —This species, also peculiar to the Mississippi* Valley, 
is quite unique in this genus by its dioici’ty, though its nearest ally, the 
last mentioned one, approaches it. From this it is readily distinguished 
by the absence of the velum, by the deep brown color of; the microspores 
and the larger size of the macrospores; in these last I notice the peculi¬ 
arity that the ridges themselves which separate the faces of the spores are 
also more or less tuberculated, while in other species they are quite 
smooth. 
* * Velum complete. 
14. I. Nuttallii, A. Braun in Herb. Similar to the last two species, 
with an almost globose slightly grooved trunk and 20 to 60 slender bright 
green leaves, 3 to 9 inches long, with only 3 peripheral bast-bundles; spo- 
