Mr. R. Shelford's Studies of the Blattidx. 517 



Qumber 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 larvae 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-larvse 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 Folyhia, which was sent 

 home by the collector, M. F. Geay. In conclusion, we may 

 regard these two genera, Attaphila, and Sphccophila, 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 tioo genera : — 



Colour. 



Pubescence. 



Size. 



Shape. 



Keduction of eyes. 



Vertex not covered by pronotum. 



Shortness of legs. 



One-juinted cerci. 



Differences hetween 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. 



