420 AXTGUSTA EUCKER, 



of tlie flagellum for cliaracters indicative of tlie species since these 

 joints Vary in length and thickness as do tlie joints of tlie head and 

 thoracic appendages tliough to a much greater extent. The drawings 

 of this appendage, Avhich are all made to the sanie scale, woiild show 

 the uselessness of snch a procedure. The second Joint in one flagel- 

 Inm is twice as long as tliick while in another it is fonr times as 

 long as thick. The difference is even greater in the terminal Joint. 

 All conditions of Variation in size appear among these joints. 



As variable, and more so. than the size of the joints in the 

 flagellum is the nnmber of short setae on the sternum of the cephalo- 

 thorax of Koenenia. Sometimes twelve and never less for the adult, 

 sometimes thirteen, sometimes fourteen. offen fifteen, and sometimes 

 sixteen hairs were present. These setae were arranged in a 

 posterior (sometimes very irregnlar) row across the sternum. 

 Anterior to this were two rows running posteriorly and slightly 

 diägonally to form a V. 



I 



IT. Post-emll)ryonic Stages. 



AVhen I began collecting for this piece of work I would havc [ 



been very much surprised if I had been told that the above points ' 



laid down as characteristic of the species were more important than j 



the three pairs of hing sacs, or the group of sense organs on each \ 



side of the head. I would liave been still moi-e surprised if I had i| 

 been told that I could not recognize a younger ontogenetic stages of 

 Koenenia when I was on the lookout for'them at all times. To be 



sure they would be smaller, the number of hairs usually met witli ' 



in the adult would not be present, and the reproductive appendages i 



would be poorly developed. Yet the lung sacs, the stiif hairs on the .\ 



third metatarsal Joint and the lateral sensory organs would be ' 

 present. However, if the metatarsal seta failed, the lateral sensory 



hairs and the condition presented by the lung sacs of the third, i 



fourth and fifth segments would be evidence enough. Tims with /; 



implicit faith in these abdominal appendages as a guide for the ' 

 younger stages of Koenenia, I continued collecting. 



Material obtained on April 26th revealed a very active specimen ■; 



which, because of its size, lack of certain hairs, the peculiar appear- j 



ance of the reproductive organs, and the stiif seta on the third i 

 metatarsal Joint, which did not fail, I believed to be a youngei 

 stage of the Texan Koenenia — but one glance at the condition oi 



