590 
Praia.—A Review of the Genera 
of 1880 as regards the spines, but omits any reference to the fruit. In the 
generic key which precedes his diagnosis, Pax has substituted for the 
character which in 1866 Mueller believed to be the only mark of distinction 
between Erythrococca and Claoxylon , alternative characters derived from 
the stamens and stigmas. 1 
Up to this point the history of Erythrococca has been that of a mono- 
typic genus. In 1894 a new phase in this history was initiated by Pax, 
whose prolonged and fruitful study of the African Euphorbiaceae has been 
so rich in interesting results. In 1889 Schweinfurth collected in Arabia 
a plant previously obtained there by Defiers. This species, treated by 
Defiers as perhaps a Mercurialis (Voy. Yemen, 203), was distributed by 
Schweinfurth (PI. Arab. Fel. exsicc. 933) as a Claoxylon. In 1892 Schwein¬ 
furth and Riva met with the same species in Abyssinia. On this occasion, 
as the sheets he distributed indicate, Schweinfurth concluded that the plant 
was not a Claoxylon , but must be either an Erythrococca or the type of 
a new genus. Deciding in the latter sense, he named the species Deflersia 
erythrococca , Schweinf. (Penzig in Atti Congr. Bot. 1892, Genova, 359). In 
1894 Pax referred this plant to Erythrococca , as E. abyssinica, Pax (Engl. 
Bot. Jahrb., xix. 87); to this view Schweinfurth has since assented (Bull. 
Herb. Boiss., vii, app. 2, 306). If Erythrococca be indeed a valid genus, this 
action is fully justified ; Deflersia , Schweinf., and Erythrococca , Benth., 
agree in having perulate buds, accrescent indurated stipules, both extra- 
staminal and interstaminal receptacular glands, discrete hypogynous scales, 
and free, linear, plumosely laciniate stigmas ; they mainly differ in that the 
ovary in Deflersia is glabrous, but in Erythrococca is strigose, while in 
Erythrococca the stipular spines and the receptacular glands are larger than 
in Deflersia. Along with E. abyssinica , Pax added two other species to 
Erythrococca (Engl. Bot. Jahrb., xix. 88). One of these species, A. Fischeri , 
Pax, is interesting because it serves as a connecting link between Deflersia , 
Schweinf., and Clao ylon § Adenoclaoxylon, Muell. arg.; the other, E. bon - 
gensis , Pax, is a genuine Adenoclaoxylon. In thus widening the limits of 
Erythrococca , Pax has not stated what differential characters were relied on 
by him in distinguishing the genus from Claoxylon , though he has made it 
clear that he was not practically influenced by the criterion on which 
Mueller relied in 1866, 2 and that he was not guided by the criteria employed 
by himself in 1890. 3 The omission was, however, rectified in 1895 (Engl. 
Pflanzenw. Ost-Afrik., C, 238), when Pax supplied a new diagnosis; the only 
1 The characters adduced ( 1 . c. 47) are: Erythrococca ; stamens 3-6; styles short, plumosely 
laciniate, free from the base : Claoxylon; stamens usually numerous; styles linear, entire. 
2 Of the three species thus for the first time added to Erythrococca , the female flowers and fruits 
were unknown in E. Fischeri and E. bongensis , and although the female flowers of E. abyssinica 
are described there is no account of the fruit. 
3 Claoxylon lasiococcum , Pax (Engl. Bot. Jahrb., xix. 87), described at the same time as these 
three species of Erythrococca, has plumosely laciniate and not entire stigmas. 
