396 Sir R. Schomburgk on some Grasses and Sedges their operations according to circumstances, and when unimpeded m them, of the beauty and fitness of their architectural eleva-tions. EXPLANATION OF PLATE XXIII. Fig. 1. Stethorectus ingens, female, natural size. Fig. 2» Ditto male ditto : a, wing, natural size. The following are mag-nified: b, labial palpi ; c, maxillary palpi ; d y mandible of the female ; e, mandible of male ;/, antennae of the male. XLI. — Description of some Grasses and Sedges from the East Coast of Demerara, with Remarks on the Geographical Distri-bution of the Species. By Sir Robert Schomburgk, Ph.D., Member of the Imperial Academy Nat. Curios. &c. The grasses and sedges are to a flat alluvial soil what the forests are to a hill-side ; their interlacing roots render the soil firm and prevent it from being carried away by the surface waters, which chiefly during freshets under the tropics commit such ravages upon low lands. The grassy sward protects besides the ground beneath from the direct rays of the sun, which possess such in-creased power in the equatorial regions. As great as the benefit derived from these circumstances may have proved to certain localities on our globe, if the use which the grasses afford to mankind rested only upon these circumstances, they would never have been considered of that vast importance which is attached to this natural family. If we set aside that their seeds afford nourishment to millions of human beings, their herbage serves as food to millions of cattle which in their turn contribute to the support of mankind. It is not my object to dwell here on these important points, but merely to give an enumeration of some grasses and a few of the sedges which occur in the intermediate neighbourhood of the sea-coast in Demerara, and the greater number of which are used as fodder. It must not be considered that this list contains all the Graminacese of that locality, — their number might be tripled ; they were merely the result of short botanical excursions in the neighbourhood of Georgetown and to Mon Repos, a sugar-plantation on the east coast of Demerara ; a few I received from Mr. Garnett at Cuming's Lodge, about six miles east from Georgetown. This small collection was sub-mitted to the examination of Professor Nees von Esenbeck, the great illustrator of Graminacese and Cyperacese, who with his usual kindness has described those peculiarities in which the Demerara specimens deviate from former descriptions of species. It is worthy of observation that these deviations amounted in no instance to specific differences. I have added the vernacular names under which the species and
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