terminal segment in some male Hemiptera. 425 



chroma lata, and P. hardivicki, be compared, it will be 

 understood how difficult it is to recognise the homo- 

 lo,s;ous parts ; and it is not easy to see how such very 

 different organs can have the same function. Indeed, 

 the great variety existing in so important a part, and 

 one so closely connected with the continuance of the 

 species, will, I think, prove to be very difficult of expla- 

 nation to those who adopt the theory of a common 

 ancestor for species systematically allied. 



Finally, I may remark that I have not observed any 

 variation whatever in the parts in individuals of the 

 same species. 



Explanation of Plates XII., XIII., & XIV. 



PLATE XII. 



Fig. 1. Tesseraioma malaya, Stal, viewed from above; La. 

 lateral appendage, i. inferior accessory process, c. rectal-caiida. 



Fig, 2. T. nigriyes, Dallas, viewed from above; I. a. lateral 

 appendage, i. inferior accessory process, c. rectal-cauda. 



Fig. 3. T. papillosa, Drury, viewed from above, with one of the 

 lateral appendages, I. a., partially rotated or lifted. 



Fig. 4. Eusthenes pratti, Distant, viewed from behind and 

 slightly from above ; I. a. lateral appendage, i. inferior accessory 

 process, c. rectal-cauda, l.p. superior lateral process. 



Fig. 5. Stilida indecora, Stal, showing the normal position of 

 the terminal segment, t.s., when retracted. 



Fig. 5 a. Terminal segment of S. indecora, viewed from above ; 

 I. a. lateral appendage, i. inferior accessory process, c. rectal-cauda. 



Fig. 5 b. S. indecora, after the rectal-cauda, diaphragm, and one 

 lateral appendage have been dissected off, viewed from above and 

 a little in front; La. lateral appendage, i. inferior process, o. 

 cedeagus consisting of semimembranous corrugated substance, o. «. 

 style of oedeagus, t. theca. 



Fig. 6. Edessa ritfo-marginata, DeGeer, viewed from above ; 

 L a. lateral appendage, i. inferior accessory process, c. rectal-cauda, 

 l.p. superior lateral j)rocess. 



Fig. 7. The same, viewed from behind and a little from below ; 

 the rectal-cauda is very large, and extends all along the middle of 

 the figure : the lower part is not quite correctly rendered by the 

 artist. 



