Mr. R. Shelford’s Studies of the Blattide. api ly 
aumber of cells enclosed in a common covering of paper, 
and the entrance to the nest is by one orifice in the floor 
of the nest. The mother wasp feeds the larvee with insects 
or spiders that she brings to them, and it is probable that 
the symbiotic cockroaches living on the floor of the nest 
feed on any small fragments of food that may drop down 
from the wasp-larve in the cells above. I owe this sug- 
gestion to my friend Vicomte R. du Buysson, who discovered 
the cockroaches in the nest of the Polybia, which was sent 
home by the collector, M. F. Geay. In conclusion, we may 
regard these two genera, Attaphila and Sphecophila, as 
affording an admirable demonstration of convergence in 
development, a result which we may fairly assume to have 
been brought about by very similar modes of life, viz. 
symbiosis with social Hymenoptera. The following tables 
show more graphically the similarities between the two 
genera and their dissimilarities, and it will be seen that 
whilst the former are in the main superficial and obvious, 
the latter are deep-seated and of great taxonomic import- 
ance, showing that the genera have arisen from totally 
different stocks, 
\ 
Features common to the two genera :— 
Colour. 
Pubescence. 
Size. 
“ Shape. 
Reduction of eyes. 
Vertex not covered by pronotum. 
Shortness of legs, 
One-jointed cerci. 
Differences between the two genera :— 
ATTAPHILA. ¢. SPHECOPHILA. ¢. 
Third antennal joint short. Third antennal joint long. 
Ocelli absent. Ocelli present. 
Tegmina and wings present. Tegmina and wings absent (? in 
nymphs only), 
Supra-anal lamina trigonal. Supra-anal lamina semi-orbicular. 
Styles absent. Styles present. 
Femora armed beneath. Femora unarmed beneath. 
Tarsal arolia present. Tarsal arolia absent. 
