EXPLANATION OF THE PLATES. 



Plate DXL. Plntjs monticola. 



1. A branch with staminate flowers, natural size. 



2. A staminate flower, enlarged. 



3. Diagram of the involucre of the staminate flower. 



4. An anther, side view, enlarged. 



5. An anther, front view, enlarged. 



6. A branch with pistillate flowers, natural size. 



7. A pistillate flower with its peduncle, enlarged. 



8. A scale of a pistillate flower, upper side, with its ovules, enlarged. 



9. A scale of a pistillate flower, lower side, with its bract, enlarged. 



10. A cluster of winter branch-buds, natural size. 



11. Tip of a leaf, enlarged. 



12. Cross section of a leaf, magnified fifteen diameters. 



Plate DXLI. Pinus monticola. 



1. A portion of a branch with cones, natural size. 



2. A cone-scale, upper side, with its seeds, natural size. 



3. A seed, natural size. 



4. Vertical section of a seed, enlarged. 



5. An embryo, enlarged. 



