72 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



%-y2 'iK-li broad near the base, fertile blade %-^ inch broad. Limestone cliffs in 

 Eastern Iowa. Bot. (y't/s., VIII., igg, Plate III. 



Resembles C. rlnzophyllus, Init may be readily distinguished by the 

 soHtary axial bundle of the stipe, destitute of the e.xtra-fascicular scle- 

 renchyma, the thinner and narrower fronds, acute base, simpler vena- 

 tion, and short sori. The typical form has two distinct bundles at the 

 base of the stipe, which coalesce above into one ; these are accomj^a- 

 nied by a dark thread of sclerenchyma situated outside each bundle, and 

 usually anterior to it, which unite to form a single thread after the union 

 of the bundles, or, when lateral, remain as distinct lateral threads. In 

 the variety the bundle is simjile throughout, and has no external scle- 

 renchyma. Again, in the tyi:)ical form the base of the frond is never 

 strictly wedg-'-sha|)e, as in the variety, but, however much reduced, has 

 still some indication of auricles. It is the opinion of Mr. George 

 E. Davenport (in litt. ) that this "is only a weakly growth, in which 

 the plants have simply failed to develop their full characters." a con- 

 clusion which some of the facts do not ajjpear to corroborate. The 

 small area covered by the ])lants was within a few yards of as large 

 and thrifty a growth of the typical walking-leaf as one is likely to 

 find. Small plants have been gathered by the writer and others in 

 various parts of the State, but none of them show the distinctive char- 

 acters of the variety. A specimen in the herbarium of the Chicago 

 Academy of Sciences, collected by A. H. Curtiss in Virginia, more 

 nearly approaches the variety in external appearance than any other 

 yet seen by the writer; the fibro-vascular bundle, however, is in every 

 respect typical. If this be only an individual form, it is still interest- 

 ing, as all the deviations from the fyi^e are in the direction of the Sibi- 

 rian species, C. Sibiricus, the only other species known. The walking- 

 leaf is not a rare fern in Iowa, and the discovery of the variety in other 

 localities may confidently be expected. • 



Corrections and Explanations. 



The following are corrections of i)revious contributions and some 

 additional notes on the present one: 



In Contr. No. \'., for Kiunuii Co., read Enmiet Co. 



Aphylloii fasciciilatiuii (No. 523) is to be dropped from the catalogue. 

 ITpon re-exaniinalion, the specimens ])rove to be the same as No. 522" 

 of Contr. No. II. It {A. ii/ti/Ioniiii, T. & Ci.) is a very rare plant in 

 the State, 



