Annals of the Transvaal Museum 
263 
tains ; in P. mennelli the tarsus is shorter than in the other two, and if all 
the Serins be compared it will be seen that those of the south-western 
districts all have a longer tarsus and stouter feet than the species of the 
east and north-east, probably due to the sandy conditions of soil in the 
south-west. I feel I cannot avoid subdividing the genus and therefore 
propose to place P. leucoptera (Sharpe) in a new subgenus, Lormarinsia, 
and P. mennelli Chubb in a new subgenus, Menellia. P. alhifrons (Sharpe) 
belongs to this genus, but represents another subgenus, characterised by 
its still more powerful bill, in the mountains of East Africa. 
The next genus is Crithagra Swainson, type Serinus sulphur atus (L.), 
which is characterised by its powerful bill. Here we find the same effects 
of environment upon the species, the eastern being more or less greenish 
or yellow, the western plain grey and white, with only a little yellow on 
the rump. The typical Crithagra is yellowish green on the chest, forming 
a semicircle round a yellow throat patch, the abdomen and under tail 
coverts greenish yellow; as we proceed northwards, we find at Woodbush 
and throughout Central African mountains the greenish of the breast giving 
way to yellow like the throat and abdomen and the whole tone of the upper 
parts yellower. In the lower hills, however, we find this bird becoming 
slightly smaller and clearer yellow and at still lower levels on the littoral 
the yellowest and smallest representative of the genus occurs. The tropical 
escarpment mountain form bears the name of C. sharpei Neumann (Journ. 
Orn. 1900, p. 287) and the coastal form the name of C. shelleyi Neumann 
(Orn. Monatsb. 1903, p. 184). Unfortunately, figures were not given by 
Neumann to show the difference in size, and in consequence we find sub- 
sequent authors placing shelleyi in the synonymy of sharpei. Swynnerton 
recorded 5 . sharpei from Chirinda (cf. Ibis, 1908, p. 26) and also recorded 
specimens identified by W. L. Sclater as 5 . sulphuratus and 5 . marshalli 
from Helvetia, a little north of Chirinda. Ogilvie-Grant subsequently 
corrected the Helvetia record of sulphuratus to sharpei (cf. Ibis, 1908, p. 
280) , but said nothing about the record of marshalli, which may have been 
shelleyi, as Grant regarded shelleyi at that time as a doubtful subspecies 
of sharpei] but in a later publication (Trans. Zool. Soc. Lond. xix. No. 4, 
p. 308) Grant gave dimensions of the two forms, which he still regarded 
as only subspecies, namely, the wing length in sharpei as 77*5-84 and 
shelleyi 73’5-77*2 mm. Males of the coastal species are extraordinarily like 
the males of the dimorphous species presently to be discussed, but may be 
readily distinguished by the rather heavier bill and the yellow of the fore- 
head not meeting in the middle. The western subgroup, Crithagra albo- 
gularis (A. Smith), besides differing so markedly in colour, has a longer 
tarsus, the bill slightly smaller and the tail proportionately shorter; I 
therefore propose to place it in a new subgenus Psammospiza. 
Occurring over the western area and the south is another genus, repre- 
sented by Serinus flaviventris (Swainson), which has a stouter bill than 
Serinus, but a weaker bill than Crithagra and is remarkable for the dimor- 
phism of the sexes. Alario alario is also dimorphic and Spinus tottus is, 
to a small extent, so that this character may have some relation to the food 
supply. It is my conviction that dimorphism arises from the quality and 
abundance of food available, the male not taking so active a part in the 
parental duties when there is sufficient food for the female alone to secure 
