6 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
same name. In addition to these must be mentioned Annona sessili- 
flora Benth., which proves to belong to the genus Guatteria and must 
take the name Guatteria sessiliflora (Benth.). 
SCHEME OF THE PROPOSED SUBDIVISIONS. 
Group I. GUANABANI (SOURSOPS). 
Section 1. Euannona. Type species, Annona muricata L. 
Section 2. Psammogenia. Type species, Annona salzmanni A. DC. 
Section 3. Ulocarpus. Type species, Annona purpurea Moc. & Sessé. 
Group II. PILAEFLORAE (SILKY ANNONAS). 
Section 4. Helogenia. Type species, Annona paludosa Aubl. 
Section 5. Pilannona. Type species, Annona sericea Dunal. 
Section 6. Gamopetalum. Type species, Annona cornifolia St. Hil. 
Group III. ACUTIFLORAE (SHARP-PETALED ANNONAS). 
Section 7. Phelloxylon. Type species, Annona glabra L. 
Section 8. Atractanthus. Type species, Annona acutiflora Mart. 
Group IV. ATTAE (CUSTARD APPLES). 
Section 9. Chelonocarpus. Type species, Annona scleroderma Safford. 
Section 10. Atta. Type species, Annona squamosa L. 
Section 11. ama. Type species, Annona diversifolia Safford. 
Section 12. Saxigena. Type species, Annona bullata A. Rich. 
Group V. ANNONELLAE (DWARF ANNONAS), 
Section 138. Annonula. Type species, Annona cascarilloides Wright. 
Section 14. Annonella. Type species, Annona globiflora Schlecht. 
KEY TO THE GROUPS. 
Flowers subglobose or broadly pyramidal in bud. 
Corolla 6-petaled; petals broad, in 2 series. 
Inner petals imbricate.____..---____-____- T. GUANABANI (p. 6). 
Inner petals valvate______..---------_--- ILI. ACUTIFLORAE (p. 14). 
Corolla 3-petaled or, if 6-petaled, inner petals 
much narrower than outer or rudi- 
mentary. 
Apex of the connective broadly expanded 
above the pollen sacs; flowers of 
medium size__.._-.-/-------------- IT. PIAEFLORAE (p. 10). 
Apex of the connective not broadly ex- 
panded, scarcely exceeding the pollen 
sacs in width; flowers small_______- V. ANNONELLAE (p. 21). 
Flowers elongate and more or less triquetrous in 
bud____________------------_---------------. IV. ATTAE (p. 16). 
CHARACTERS OF THE GROUPS AND SECTIONS. 
Group I. GuANABANI (soURSOPS). 
(Section Guanabani Mart., in part.) 
Flower buds subglobose or broadly pyramidal; flowers large; petals 6, the 
outer valvate, thick, broadly ovate and usually cordate, the inner somewhat 
smaller, with the edges thinner and overlapping (imbricate), forming a dome- 
like covering over the essential parts, usually clawed at the base. 
KEY TO THE SECTIONS. 
Leaves with minute pockets or pits in the axils of 
the lateral nerves____-.-------------------- 1. HUANNOoNA (p. 7). 
