1893. NOTES AND COMMENTS. 405 
Tue ANCESTORS OF THE Cart. 
Tue above-named authors in the same communication put forth 
the hypothesis that the cats, instead of being directly related with 
the other Carnivores of the present day, are independently descended 
from the Creodont genus Palonictis. In view of the close similarity 
between the Cats and the Civets (the latter being clearly related to the 
Dogs), this is ‘‘ parallelism” with a vengeance. Does it never strike 
the promoters of such extreme views that by proving (!) the want of 
relationship between apparently closely allied animals they may be 
cutting away'the ground from beneath the foot of the evolutionist, 
since, if resemblances are, so to speak, fortuitous, why should not we 
revert to the doctrine of separate creations? That parallelism does 
exist in Nature, we are fully prepared to admit, but it is not omni- 
present. However, when once the ball is set rolling in a certain 
direction, everyone thinks it necessary to give it another push. 
AERIAL Roots OF ORCHIDS. 
Tue velamen, or characteristic external covering of the aérial roots 
of epiphytic orchids, forms the subject of a note by P. Groom in the 
last issue of the Annals of Botany. As terrestrial orchids are almost 
invariably devoid of a velamen, it is usually assumed that the aérial 
orchids acquired theirs subsequently to the adoption of an epiphytic 
mode of life, but it is suggested that the few exceptions may indicate 
the existence of the covering in a previous terrestrial mode of life. 
With a view to getting some light on the date of origin of the 
velamen, the author has made observations on Gvammatophyllum 
speciosum and species of Bromheadia, both at Singapore. The former 
is one of the few orchids which grow naturally both as terrestrial and 
epiphytic plants, and can be found growing in the jungle when it has 
happened to fall off a tree. When a terrestrial plant, the velamen is 
not only retained but even strongly developed in the soil, while the 
upwardly-growing aérial roots characteristic of the epiphytic habit, 
which Schimper has shown to be respiratory organs, are still 
developed. 
Byromheadia alticola lives in the full blaze of the sun on high tree 
tops, and has a peculiar two-layered velamen, while in B. palustris, 
which is terrestrial, the velamen is fundamentally similar, but lasts 
only for a short time, peeling off and disintegrating. This points to 
the conclusion that this covering is essentially adapted to epiphytic 
plants, and was evolved subsequently to their assumption of an aérial 
mode of life. 
The two sets of observations seem to give contradictory results. 
In the first, the velamen being more highly developed in the sub- 
terranean ; in the second, in the aérial roots; but the explanation 
is found in the fact that the function of the structure varies. In 
Grammatophyllum it is essentially an absorbent organ, which not only 
