NOTES. 207 
earth-snakes. In fact, at the Zoological Gardens in Regents park 
it has been found impossible to make them eat anything but other 
snakes. 
The pretty whip-snake, Dryophis mycterizans, has a peculiar habit, 
if caught and placed somewhere where it cannot escape, of raising 
itself up, opening its mouth, and expanding the lower jaw into the 
form of an oblong, which gives it a most ferocious appearance. 
Although I have repeatedly noticed this habit in low-country 
specimens, yet I have never seen one of the up-country snakes do it, 
though I have kept many of them. 
Very much the same aggressive behaviour is to be seen in Tropi- 
donotus stolatus, which pufis out its body in resemblance of a viper, 
while the rat-snake will often raise itself up and expand its neck 
with air, in emulation of the cobra. 
Considering how closely allied T'rimeresurus trigonocephalus is to 
the American Crofali, its custom of vibrating its tail rapidly when 
irritated is peculiar, but I do not think this habit is in any way due 
to its relationship to the rattle-snake, as I have noticed the same 
behaviour in Dipsas ceylonensis. 
In view of the discussion which recently occurred as to the species 
of Dendrophis commonly found in Ceylon, it may be of interest to 
say that when last in England I asked Mr. G. Boulenger about it, 
and he gave it as his opinion that D. bifrenalis was the common 
variety, though there was very little distinction between it and 
D. pictus. A. F. ABERCROMBY. 
21. Abnormal Chicken with Four Legs.—Some months ago a newly- 
hatched chick of the common domestic fowl was brought to me. 
The bird was peculiar in having two supernumerary legs—both on 
the right side of the body (see fig. 1). Such abnormalities in birds 
appear to be by no means uncommon. I was interested to see how 
the two additional legs were attached to the pelvic girdle, and for 
this purpose a skeleton of the specimen was prepared. Owing 
to the soft nature of the bones this process was by no means an 
easy one. 
The heads of the two additional femurs did not appear to be 
fitted into sockets, but the two bones were plastered down flat on 
the side wall of the right ischium (see fig. 2). The heads of,the two 
femurs lay quite close together, and the two bones crossed over each 
other. The interesting point about these two limbs was that there 
was no tibio-tarsus present. Each femur was directly connected 
with the tarso-metatarsus. The femur and tarso-metatarsus of 
each supernumerary leg was the same size as the similar parts in the 
normal legs, Each supernumerary leg had only three toes. 
