STRUCTURE.] ANOMALIES DEHISCENCE. 345 



to a Flora of Ceylon.) In Cycads the anthers are sessile, 

 3- or 4-celled, open vertically, and' are scattered over the face 

 of a bract metamorphosed into the hard scale of a cone. 

 Conifers, too, present some singular anomalies, which have 

 been studied by Zuccarini. (See Ray Reports, 1845.) 



With regard to deviations from the usual mode of dehis- 

 cence, Brown observes (Linn. Trans, xiii. 214.), "that they 

 are numerous : in some cases consisting either in the aperture 

 being confined to a definite portion, generally the upper 

 extremity of the longitudinal furrow, as in Dillenia and 

 Solanum ; in the apex of each theca being produced beyond 

 the receptacle of the pollen into a tube opening at top, as in 

 several Heathworts (Ericaceae) (Plate III. fig. 22.); or in the 

 two thecse being confluent at the apex, and bursting by a 

 common foramen or tube, as in Tetratheca (see Plate IV. 

 fig. 4.). In other cases a separation of determinate portions 

 of the membrane takes place, either the whole length of the 

 theca, as in Witch Hazels (Hamamelidacese) and Berberids, 

 or corresponding with its subdivisions, as in several Laurels 

 (Lauracese), or lastly, having no obvious relation to internal 

 structure as in certain species of Rhizophora." In Laurels 

 and Berberids the anthers are technically said to burst by 

 recurved valves (Plate IV. fig. 10, 11.), that is to say, the 

 dehiscence does not take place by a central line, but the 

 whole face of the cell separates from the anther, and curls 

 backwards, adhering to it only at the apex, to which it is, as 

 it were, hinged. 



In Rhizophora, above alluded to, the anther is said by 

 Mr. Griffith to be compressed, with the edges anterior and 

 posterior, and to open by the separation of a valve from the 

 sides, when the pollen is seen lying in socket-like excavations, 

 the upper portions of which may be traced on the inner face 

 of the valves. (Trans. Med. fy Phys. Soc. Calcutta). Mr. 

 Griffith rightly explains this singular structure to be a mo- 

 dification of dehiscence, caused by the adhesion of the valves 

 to each other at the usual line of fissure, and their separation 

 from the connective. It is not therefore quite correct to say 

 that the dehiscence of Rhizophora bears no obvious relation to 

 internal structure; it is of the same nature as that of Laurels, 



