94 Bulletin Wisconsin Natural History Society. [Vol. 9, No. 3. 



Species. — The present study has occasioned the naming of 

 several new species, while at the same time a number of others 

 have been relegated to the synonmy. The number of species of 

 Tetragoneuria is therefore hardly increased. A list of the species 

 and their synonymy is given at the end of this paper. 



Acknowledgements. — I have already stated from whom speci- 

 mens were received. To these gentlemen I wish to express my 

 thanks and sincere appreciation of their kindness. To Mr. Wil- 

 liamson and through him to Dr. Ris I am indebted for the use 

 of the notes of the latter on the types in the de Selys collection at 

 Brussels. Had it not been for the careful notes of Dr. Ris, a 

 solution of the synonymy would have been impossible. Through 

 his notes I have been enabled to ascertain the exact values of 

 such forms as complanata. basiguttata and costalis, though in the 

 latter case Dr. Ris has expressed his doubt of the specimens under 

 that name in the de Selys collection. 



Dr. Walker has sent me notes on several specimens of canis 

 in his collection and also some suggestions on the color variation 

 of T. cynosura. 



Dr. Calvert's paper on Burmeister's types of Odonata has 

 been very useful. Owing to his exact description of the type of 

 semiaquea it is possible to refer semiaquea to the position it 

 should properly occupy. 



Of all the species described only costalis and spinosa have not 

 been seen by me. The latter is very rare in collection and has 

 been confounded with canis by most recent writers. Spinosa is 

 probably a southern species which would account for its rarity 

 in collections. 



Little attempt has been made at accurate descriptions of the 

 body pattern, since they are practically identical in all species. 

 Mr. Williamson's extended description will serve as the mean 

 for all other species of the genus. 



The wing photographs shown with this paper have been fur- 

 nished by Mr. Williamson. Originally they were intended to 

 show the complete stages of color development found in one 

 species ; and such, with the exception of the wings in which the 

 color reaches the nodus, is actually the case in T. cynosura. 



