I. THE CHLOROPHYLL-TISSUE, ON TRANSVERSE SECTIONS, IS ARRANGED IN RINGS ROUND THE VASCULAR BUNDLES. THERE ARE MOTOR-CELLS BETWEEN THE RIBS, AND THE STOMATA ARE SUNK AND OCCUR ON BOTH FACES. _Cynodon Dactylon._ The larger lateral nerves have as a rule three smaller ones between each pair, hardly projecting as ribs. Chlorophyll chiefly in a ring round the vascular bundle. Long hairs on lower surface, a few papillæ above. Motor-cells in each shallow furrow. Short cells occur between the long epidermal cells over the bast-region. The Panicums also come here, and differ according to the disposition of the sclerenchyma sheaths around the bundles. II. THE CHLOROPHYLL-TISSUE IS BETWEEN THE VASCULAR BUNDLES, AND NOT CONFINED TO RINGS SURROUNDING THEM. +A. Conspicuous lacunæ between the vascular bundles. Stomata on both faces. Motor-cells occur.+ Lacunæ large and rectangular. Motor-cells confined to a flanking line on each side of the mid-rib. _Glyceria aquatica._ Leaves folded and in section +V+-shaped, hardly keeled, with sclerenchyma at apex. Motor-cells each side of the mid-rib only. The large square or rectangular lacunæ bounded by stellate cells. Papillæ on epidermal cells. Vascular bundles midway between upper and lower surfaces. _Glyceria fluitans._ Section +V+-shaped and keeled, the roof of each polygonal lacuna arched, hence the “ribs” on the upper surface are between the vascular bundles. The latter lie nearer the lower epidermis. The epidermis has papillæ. _Catabrosa aquatica_ and _Hierochloe_ also come here, the former with small lacunæ, the latter with larger ones chiefly towards the upper surface of the leaf. _Digraphis_ is also apt to have a few air cavities near the mid-rib. +B. Lacunæ none, or inconspicuous, the chlorophyll-tissue filling up between the ribs.+ (_a_) Upper and lower leaf-surfaces parallel, or nearly so, and much alike, the ridges being very low or obsolete. Stomata equal or nearly so on both surfaces. (1) Motor-cells absent; vascular bundles feeble and very few. _Mibora verna._ The small leaves are flat, or nearly so, and have three isolated and very feebly developed bundles, devoid of girders or sclerenchyma bands. (2) Motor-cells present, vascular bundles of various orders, with sclerenchyma bands or girders. * _Leaf keeled, and folded--not inrolled. Motor-cells confined to the neighbourhood of the mid-rib. No hairs._ † _Motor-cells conspicuous and conjoined into a band above the mid-rib._ _Dactylis glomerata._ Keel pronounced, with one large vascular bundle and a sclerenchyma band occupying its crest. Motor-cells forming one conjoint band along the upper course of the mid-rib only. Stomata on both faces, but no hairs or thick cuticle. Ribs low, and all bundles have feeble girders. A little sclerenchyma at the margins. A few pale cells in the chlorophyll-tissue.