THE BRITISH RACES OF BUTTERFLIES. 1 
its southern parts, we find an entirely different insect from the one 
just mentioned. It is an unmistakable vulgaris, quite similar to the 
races of Central and Southern Europe, which only betrays its northern 
origin by the constant character of the underside (bright yellow 
ground colour). In the male the apical crescent is broken up into a 
series of triangular patches at the end of the nervules and is generally 
of a very pale grey colour. In the females it is of the same colour 
and in many specimens it is altogether lacking; these seem to be more 
frequent in England than on the Continent; in typical vulgaris from 
Tuscany, all the grey markings vary in extent and colouring in 
a more or less parallel way, but specimens with the marginal mark- 
ings absent and the discoidal round spots and triangular costal patch 
standing out prominently, such as in some English ones (forma api- 
cenudata, NOM. nov.), never occur. 
In England vulyaris has two broods, but though the second one 
does show the napaeae characters to a certain degree, the difference 
between the two generations is far from reaching that which it reaches 
in the south of Kurope, culminating in meridionalis, Stdgr. 
In my English napzee the black markings of the upper-side are 
much deeper in colouring than in the first generation from the same 
locality and they are more sharply defined; on the underside the 
green veins are narrower and paler, but they do not disappear near the 
margin, as is the case in napacae from the south of Hurope. 
The second British race of napi just mentioned does not seem to 
differ much from the ones which inhabit the northern parts of Central 
Europe, but it certainly has amongst them the one which differs most 
from my Italian vulgaris. I propose the name of septentrionalis 
for this northern vulgaris race of napi, laying stress on the fact it is 
smailer and slighter in build than true vulyaris, that it has a bright 
yellow under-side in most specimens, that many females exhibit a 
lack of the marginal pattern on upper-side, that the difference between 
the spring and the subsequent broods is much less marked than in 
the typical Italian vulyaris. My typical series is from Westcliff-on- 
Sea; other specimens from Epping Forest and other localities are 
slightly different. . 
An interesting experiment was made by Mr. J. W. H. Harrison, who 
bred napi sub-sp. vulgaris in the open in Durham, from ova laid in April 
in Tuscany by females collected by me for the purpose; the butterflies 
emerged in June and, comparing them with the Tusvan and the English 
napt, the following observations were made:—(1) The insects were 
small and slight in build, even more so than English specimens ; 
(2) the underside had acquired the bright yellow colour which marks 
the specimens of the British Islands; (3) the upper-side had preserved 
the characters of the spring brood, whereas in Italy they would at that 
season have exhibited the characters of napaeae ; but (4) on the under- 
side the green neuration had acquired a distinct napaeae look, such 
as never occurs in specimens from a British stock, even in the height 
of summer and in the south of England. Thus in the latter instance 
alone does heredity seem to have acted, the other characters having 
been entirely modified by the influence of environmeut on the develop- 
ment of the individuals; the result was rather unexpected, as one might 
have believed that seasonal dimorphism would have been the last 
character to get fixed by heredity. It shows that experiments of this. 
