300 Mr. J. Miers on the Ehretiaceas. 



XXXIX.— On the Ehretiaceffi. 

 By John Miers, F.R.S., F.L.S., &c. 



[Continued from p. 210.] 



Crematomia. 



I have already alluded to this group of plants, which I have 

 separated from Ehretia : it forms a series distinguished by 

 very salient characters, the type of which is the Bourreria 

 exsucca of Jacquin, a plant hitherto very indistinctly described 

 and confounded with others. From a flower of the original 

 typical plant, contributed by Jacquin himself, from herbarium 

 specimens, and assisted by an analytical drawing of the struc- 

 ture of the fruit taken from a living plant, I have been en- 

 abled to complete the characters of the genus here proposed 

 under the title of Crematomia, a name derived from Kpe^aw, 

 sus^endo, and To^r), sectio, on account of its four carpellary 

 achenia, suspended by stiff threads from the summits of a 

 divided free axile column, somewhat after the manner of the 

 suspended carpels in Gouania, many Cruciferce., UmhelUfera>, 

 and Geraniacew. The calyx is constructed as in Bourreria, 

 only that its valvate segments adhere more firmly together, 

 often splitting irregularly, by the swelling of the corolla and 

 fruit, into two or three unequal divisions. The corolla is 

 tubular and fleshy, with a border of five orbicular segments, 

 shortly unguiculated and cordately auriculated at their base ; 

 the stamens are often pilose at their base, with anthers like 

 those of Bourreria ; so also is the style, only that it is always 

 more deeply cleft for a distance never less than one-fourth of 

 its length. The ovary is subconical, seated on a fleshy disk, 

 and has a placentation similar to that already described in 

 Rhahdia, Cortesia, Ehretia, and Bourreria. The drupaceous 

 fruit has a thick coriaceous pericarp, that falls away, leaving 

 a quadrately obovate cremocarp, which ultimately splits along 

 its four angles, at first into two and afterwards into four equal 

 achenia, angular within, flatfish on the dorsal face, and some- 

 what winged on the margins, the dorsal side being thick and 

 of a remarkable spongioid texture, composed of numerous very 

 long narrow cells, which radiate towards tlie periphery, all 

 covered by a reticulated membrane. A slender central column 

 is found in the axis, whicli s])lits to the base into two parts 

 that again subdivide, forming four equal, erect, rigid, aristi- 

 form supports, which are suddenly reflected at the summit 

 into as many rigid funicular chords, whence the aclienia are 

 Kns])ended at a point near tlieir base. It is requisite that the 

 fruit shoukl dry in the open air to exhibit this structure com- 



