| 
) 
; 
Proceedings 63 
only ejected when pressure is brought to bear against the spines, 
and is not under the control of the caterpillar; the most venomous 
species may be allowed with impunity to crawl over the hand 
so long as no pressure is brought to bear that would cause the 
points of the spines to touch the skin. In the Saturniadae the 
spines are arranged in branching clusters springing from the 
tubercles, varying a good deal in the different genera. In Azfo- 
meris and Dirphia the spines are tree-like and are very long on 
the Ist, 2nd, 11th and 12th segments. In Hyperchiria they 
are more even in length and more spreading, so that they form 
a close mat over the body. In A¢tacus they are minute and 
scattered. 
In the Cevatocampidae the spines are short and horny, often 
arranged on long fleshy protuberances as in Citheronia brissotit. 
These large and powerful caterpillars of the Saturniadae and 
the Ceratocampidae, though the function of the spines is pas- 
sive, are able to inflict a painful wound by swinging the head 
and thorax and striking an intruder with the spines. 
My experience with the venomous caterpillars of Brazil tends 
to point to the Megalopygidae as the most virulent of all the 
families; in this family the spines are clustered in the form of a 
rossette round the tubercles, not branched, and they are gener- 
ally concealed by long silky hairs of various forms. I will con- 
clude this paper with the account of an experiment with one 
of this family, AZ. dorstmacula,made in Sao Paulo in 1878 and 
published in the Proceedings of the Literary and Philosophical 
Society of Liverpool in the same year. 
The note is as follows: 
“On February 28th, 1878, I found a beautiful species of 
caterpillar about an inch and a half long and very thick in pro- 
portion to its length. The whole body is covered with long 
red-brown hairs which grow in tufts arising from the centre of 
each segment, and at the base of the long hairs are bunches of 
venomous spines, which are quite concealed by the hairs. The 
body is very soft and fleshy and of a paler colour than the hairs. 
There are six pairs of abdominal legs, the first and last pairs, 
however, not being fully developed. The head is very small, and 
is when eating quite covered with a fleshy mantle formed by 
