344 MR. L. LEWTON-BRAIN ON THE ANATOMY 
§§ Asperities on both surfaces. Stomata more abundant above. 
AGROSTIS STOLONIFERA. Cambridge. August 1900. 
Leaf rather thin. Bundles numerous, of three orders. All have double sheath. 
Stereome forms bands above and below all bundles; some of larger bundles girdered. 
Stereome-bands also under lower epidermis opposite the grooves. 
+t Motor cells inconspicuous. Epidermis rather strongly cutinized. 
§ Asperities on ribs below. Stomata on both sides. 
PHLEUM PRATENSE (Pl. 39. fig. 46). Ilford, Essex. August 1901. 
Short sharp asperities below bundles. Stereome forms girders below to nearly all 
bundles, girders above also to larger ones and bands above smaller bundles. 
Swanton Morley, Norfolk. June 1901. 
Practically as above, but there are no asperities. Also the vascular bundles are more 
numerous and some of the smallest are not girdered below. 
§§ Asperities on both surfaces few. Stomata more numerous above. 
AGROSTIS VULGARIS. Edinburgh. July 1901. 
. Ridges rounded. Lower side flat. All bundles have double sheath, though not 
always conspicuous. Stereome forms girders to larger bundles and bands above and 
below smaller bundles; also bands occasionally between the ribs, under the lower 
epidermis. 
tt Stereome relatively inconspicuous, and rarely forming true or complete girders. 
i Motor-cell groups restricted to two series flanking the midrib. Hairs few and short. 
Stomata far more numerous above. 
Poa BULBOSA (Pl. 39, fig. 47). Yarmouth, Norfolk. May 1902. 
Leaf small, narrow, and rather thin. Lower epidermal cells not flat. Stomata much 
more abundant above than below. Sheaths not very well marked, especially in smaller 
bundles. Stereome in feeble bands above and below or above or below bundles. 
1i Motor cells between all the ribs. Stomata more numerous above. 
§ Motor-cell groups conspicuous. Short, sharp, stiff hairs above. 
|| Chlorophyll-tissue tending to form rings round the bundles. Hairs few. 
Poa RIGIDA (Pl. 37. fig. 23). (See p. 334, above.) 
[|| Chlorophyll-tissue normal. Hairs many. 
CYNOSURUS CRISTATUS. Grantchester, Cambs. August 1900. 
Ribs rounded and fairly prominent on both sides. Margin rounded. Bundles of 
three orders ; larger ones have both sheaths well marked, but in smaller ones the inner 
sheath is not well seen. Stereome-bands above and below all bundles, and in two cases 
below the motor cells. 
Melrose. June 1901. 
As above, except that stereome is more abundant; it forms girders to all bundles 
below and to larger ones (except that in midrib) also above. 
