90 
Notes on Hybrids of Tephrosia bistortata, Goetze, and 
T. crepuscularia, Hb. 
By J. W. Tutt, F.E.S. Communicated October 28th, 1897. 
THE specimens of Zephrosia bistortata and T. crepuscularia, 
together with the hybrids between these species that I exhibit- 
to-night, are the results of a series of experiments carried out by 
Mr. A. Bacot and Dr. W. S. Riding during the past summer. 
As there has been considerable discussion, as to the specific dis- 
tinction of these species, it may be well to premise my notes on the 
exhibit by saying that the difference between those who hold that 
these are one and the same species, and those who hold that they are 
distinct, is merely a matter of terms. Even Mr. Barrett, the strongest 
supporter of the one species view, does not fail to find sufficient 
distinction to enable him to speak of them as “ varieties” or “forms ” 
and to the evolutionist the scientific result is not affected by the 
term applied to them. So long as they are distinct and recognisable 
as distinct forms it is not worth while arguing as to whether they are 
what is termed one species or two ; as I have said, it is only a difference 
of degree, not a difference of kind. 
It will be seen that there are considerable differences between the 
two insects operated on by Mr. Bacot and Dr. Riding. These 
differences may be summarised as follows :—(1) Zephrosia bistortata 
is of an ochreous (often tending to ferruginous and fuscous) ground 
colour ; it occurs in the British Islands in March to April, and again 
in July; it is widely distributed in the southern and western counties 
of England and in Scotland, and is found in the greater part of the 
Palearctic and Nearctic regions. Its second brood differs from the 
first in being usually smaller, of a dead white colour, and without the 
ochreous suffusion of the first brood. The warm-tinted early brood 
of this species is known as var. adzefaria, Haw. ; the Scotch (Perth 
and Moray) specimens are the nearest approach we have in Britain 
to the more fuscous Continental type = dzstortata, Goetze ; the small, 
pale second brood is known as var. consonaria, Stephs. (2) The 
second species, Z: crepuscularia (biundularia), has a white ground 
colour ; it occurs in the British Islands in May and June, z.e. its time 
of appearance falls between the two emergences of Z: dzstortata ; it 
is never double-brooded in nature, is widely distributed in the 
midland and northern counties of England, is found throughout 
Ireland, overlaps 7! dzstortafa in the southern and south midland 
counties of England, and so far is unknown in Scotland. It appears 
to be widely distributed in Central Europe, but has not yet been re- 
