swingle: a new genus of kumquat oranges 169 



Fortunella approaches Atalantia and differs strikingly from Citrus 

 in having only two collateral ovules near the top of each cell, whereas 

 Citrus has 4-12 ovules to a cell. Fortunella differs from Atalantia 

 in having twice as many stamens (four times as many, instead of twice 

 as many, as the petals), and in its general agreement with Citrus in 

 twig, leaf, spine, flower, and fruit characters. 



The capitate stigmas of all the species of Fortunella contain large 

 oil glands imbedded in their substance, which renders them cavernous.^ 

 (See fig. 1.) The stigma of Citrus contains a few scattering oil glands, 

 sometimes one in every space between the radially arranged and ex- 

 panded stylar canals; but these glands are very near the surface and 

 relatively so small that the stigma lacks entirely the cavernous struc- 

 ture characteristic of Fortunella.^ The leaves show very many more 

 oil glands on the underside than in any species of Citrus, often ten times 

 as many. 



In superficial fruit characters Fortunella agrees with the Australian 

 desert kumquat {Eremocitrus glauca) in many respects. The seeds 

 are very different, however, and the stem, twig, leaf, and flower char- 

 acters are so strikingly different that it is not possible to regard these 

 genera as closely related. 



There are four species of Fortunella known at present. The two 

 commonly cultivated species, the round and oval kumquats of China 

 and Japan, together with the Meiwa kumquat, comprise the sub- 

 genus Eufortunella, distinguished by several important characters 

 from the Hongkong wild kumquat for which a new subgenus, Proto- 

 citrus, is described farther on in this paper. 



THE SUBGENUS EUFORTUNELLA 



The species of Eufortunella may be distinguished by means of the 

 following key: 



Fruits globose, 20-25 mm. in diameter, 4 or 5-celled; seeds small, 

 bluntl}' rounded at tip; leaves pale and veinless below, blunt- 

 pointed 2. F. japonica. 



5 This was noticed as early as 1784 by Thunberg (Fl. Jap. 293), who said, 

 "Stigma .... intus multilocidari," in describing the round kumquat; 

 since then no one seems to have observed this fact. 



6 Penzig, O. A. J. Studi Botanici sugli Agrumi e suUe Piante Affini, pp. 53-75 ; 

 atlas, pi. 6. (Ann. di Agr. no. 116). 1887. 



