198 NEW YORK STATE MUSEUM 
confluent along the gill axis. This species has five setae on 
each side of the mentum of the labium, and appears to be dis- 
tinguished from the others hitherto described chiefly by the 
possession of a spine on the lateral margin of abdominal seg- 
ment 3. The lateral spines in this species occur on segments 
3 to 9g: in the other species on segments 4 and 5 to 9. 
The damsel flies of the following list were also collected 
sporadically during the summer and all of them were appar- 
ently common and widespread: Argia violacea, Enal- 
IZ ex Solans, lkmaAllacimna Imaeccmi, Neinal- 
{emmia ireme, Ischmura verticalis, 
Contribution to the morphology of the Odonata 
Three years ago I suggested to Mr ©. S. Thompson, who 
was then a student in my laboratory, that he investigate the 
homologies of the male abdominal appendages of the Odon- 
ata. There was then much confusion existing concerning the 
‘terminal appendages, and no extensive comparisons of those 
of the second segment had been attempted, the fragmentary 
studies of Ratzeburg, Ingenitzky and Goddard being in the 
nature of preliminary examination of a few forms. We have 
not known whether homologies are traceable through the 
two suborders. These parts being used more and more as a 
guide to relationships in the lesser groups, and as criteria of 
species, it seemed important that their nature should be better 
understood. Mr Thompson’s work was done in 1904, but the 
final preparation of his paper has been delayed by various 
causes until the present time. Meanwhile, the terminal append- 
ages have been carefully studied and fully reported upon by 
Drs Heymons and Handlirsch. The results of Mr Thompson’s 
work upon the other abdominal appendages, those of the sec- 
ond segment, and adjacent thereto, are oiven at the endyon this 
article. 
