On Azolla and Salvinia. 255 



S. cucullata, foliis subreniformibus in cucullum condupli- 

 catis, pilis solitariis e superficie ipsa exorientibus. 



S. cucullata. Roxb. Crypt. PL Cal. Jour. Nat. Hist. IV. 

 p. 470. 



Hab. — Stagnant waters. Bengal, Tenasserim Coast. 



Descr. — Much branched. Under- surface covered with brown 

 hairs, longer and with a less suddenly attenuated terminal cell. 

 Joints of the stem short, so that the leaves are all close together. 

 Roots springing directly from the stem, about 15. Leaves on short 

 stalks, subreniform in outline, so folded together that the margins 

 of the base are in contact. Hairs of the surface solitary, springing 

 immediately from the surface ; terminal cells with the same curious 

 withered appearance. Fructification not observed. 



Obs. — This species I take to be comparatively less de- 

 veloped than the preceding, founding my supposition chiefly 

 on the fact, that the leaves partly represent the immature 

 state of the same organs of S. verticillata. 



SUB-FAMILIA. — AzOLLINjE. 



Radices solitariae, basi vaginatae, apice calyptratse.* Folia 

 imbricantia, inferum immersum membranaceum. Organa 

 mascula ; fllamenta moniliformia in partibus novellis caulis 

 et ramorum. Ovula per paria cauli affixa, in involucro e folii 



* The calyptra of the roots of Azolla has probably been considered to be the 

 torn-up end of the sheath surrounding the base of each root, which can scarcely 

 have escaped observation. But it is quite a distinct organ ; the sheath at the 

 base is perforated at its apex by the young root, while the calyptra appears to 

 be a separation of its cutis, due to the development of a radicle from each cell 

 of the subjacent tissue. 



In this respect it has another curious analogy with Lemna, of the sheath and 

 calyptra of which I was aware in 1 836, long before I saw M. Schleiden's paper 

 on Lemnaceae. 



2 L 



