1854.] Linnean Society, 273 



the seed, that Oxycladus is remarkable, for Mr. Miers has shown 

 that these occur in other genera of the Bignoniacece ; its peculiarity 

 consists in the development of only one of its many ovules, and in 

 the shape of its cotyledons, which in most other instances are 

 deeply cordate, or almost bipartite at each extremity, with the 

 radicle placed between the lobes : in this genus, however, they are 

 entire, oval, and plano-convex ; in Rhigoziim they are likewise 

 fleshy, orbicular, and entire. 



The limits of many genera of Bignoniacece appear, Mr. Miera 

 adds, ill-defined, and the chai'acters derivable from the seeds much 

 neglected. Fenzl and DeCandoUe have done much in extending 

 our knowledge of the family, but the subject still requires farther 

 investigation, for he has observed many singular deviations from 

 recorded structure that have not yet been noticed. Should it be 

 found desirable to class Rhigozum with Oxycladus, the character 

 suggested for this tribe in his former paper would require modifica- 

 tion. In that of the Crescentiece, this name ought to be suppressed, 

 and that of Tanceciea substituted, with the same character there 

 indicated : all the genera of this section of DeCandolle's Prodromus 

 strictly coincide with the Bignoniacea in their completely 2-locular 

 ovarium, and in the development of their ovules on the surface of 

 the dissepiment, and they agree also with the genus Bignonia in the 

 form of their embryo : Crescentla and Kigelia, however, present 

 characters wholly at variance with the Order, because of their 

 parietal placentation. He is not, however, persuaded of the pro- 

 priety of establishing a separate order for these two genera, which 

 has been done upon high authority, when they might so well form a 

 good tribe of the Cyrtandracece . Crescentia, with its large amygdaloid 

 embryo, does not differ more widely from the CyrtandracecB, than 

 Adenocalynma does fi'om Bignonia : in habit and in floral structure 

 the two last-mentioned genera are scarcely distinguishable. 



Read also Extracts from a Letter, addressed by Dr. Edward Vogel 

 to Berthold Seemann, Esq., Ph.D., F.L.S. 



Dr. Vogel, as is well known, is attached to the expedition dis- 

 patched by Her Majesty's government for the exploration of Central 

 Africa. He quitted London on the 19th of February 1853, reached 

 Tripoli in the beginning of March ; and after a stay of several 

 months, caused partly by the delays of his travelling companion, the 

 brother of the Sheikh of Bornou, and partly by his own preparations, 

 he started southwards towards the end of June, and after passing 

 Benoulid and Soknu, reached Mourzouk on the 5th of August. On 



