Seed-vessels of Ferns, and Section of Limestone. 



Plate 7. 



I. Seed-vessel of Fern when unripe, magnified GO diameters. 2. Seed-vessel of Fern, at the 

 moment when the ring straightens itself. 3. Leaflet of liluck Maidenhair Spleenwort Fern. 



4. Two sori, or collections of seed-vesse.s, of Spleenwort Fern, magd. 12 diams. 5. Sorus of 



Hart's-tongue Fern, magd. 6 diams. 6. Tart of a leaflet of Shield Fern. 



7. Sorus, magd. 10 diams. 8. Sori of 1'olypody Fern, magd. 7 diams. 9. Sori and part of 



leaflet of Hare's-foot Fern, magd. 5 diams. 10. Thin section of Limestone, magd. 20 diams. 



II. Group of twenty seed-vessels, natural size. 12. Group of twenty seed-vessels, magd. 6 diams. 



13. Leaflet of Polypody. 14. 1'art of a leaflet ol Hare's-foot Fern. 



