Notes on Indian Botany. 179 



The characters of these three genera will then stand 

 thus: — 



Rivea. — Fruit indehiscent. Ovary 4-celled. Stigmas 2- 

 linear, cylindrical or lamellate. 



Argyreia. — Fruit indehiscent. Ovary 4-celled. Stigmas 

 capitately 2-lobed. 



Lettsomia. — Fruit indehiscent. Ovary 2-celled. Cells 2- 

 seeded. Stigma capitately 2-lobed. 



Thus limited, the genera Maripa, Legendrea, Marcellia 

 Blinkworthia ? Humbertia, and Moorcroftia, will probably 

 all be absorbed by Lettsomia, along with some of the species 

 now referred to Argyreia, such as A. acuta (Ch.), A, aggre- 

 gata (Ch.), A. f estiva (Wall.), A. setosa (Ch.), A. elliptica 

 (Ch.), thus limited, our genera will possess precision of outline 

 very favourable for the determination of their species : as they 

 now stand, that is wanting, and determination is consequently 

 most difficult, whence we now find species of Argyreia, as 

 here limited, referred to Rivea, Argyreia, and even to 

 Ipomcea. 



In the accompanying plate, I have given figures of Rivea 

 and Convolvulus, of Argyreia and Lettsomia, and of Ipomcea, 

 to compare with each other ; and lastly, as being a new and 

 little known genus, I have introduced the analysis of Lepis- 

 temon, a genus principally separated from Ipomcea by its 

 curious appendage to the stamens. 



Explanation of Plate V. 



1 . Rivea ornata. 



2. Convolvulus rufescens. 



3. Argyreia fulgens. 



4. Lettsomia aggregata. 



5. Ipomcea pileata. 



6. Lepistemon flavescens. 



