490 NEW YORK STATE MUSEUM 



longitudinal band of brown each side of the thorax, rings on femora and 

 tibiae, and obscure, interrupted, longitudinal rows of spots on the 

 abdomen. Head compact, with eyes very prominent laterally, and the 

 front somewhat swollen between the bases of the antennae; labium with 

 its mentum distinctly longer than wide, the median lobe prominent, 

 declined, minutely spinulose on its front border, with two stouter spinules 

 at the sides of the apical angle ; lateral setae seven ; mental setae six to 

 nine; movable hook slightly incurved, and sharply pointed; teeth crenate, 

 spinulose. 



Abdomen roof-shaped; segments 3-9 about equal in length, the loth 

 a minute annular segment almost included within the apex of the ninth; 

 dorsal hooks on segments 2-9, spine-like anteriorly where covered by the 

 wings, distinctly cultriform posteriorly; lateral spines on segments 8 and 



9 long and broad at base. 



Four species are tabulated below: one of these, T. spinosa, has 

 not been hitherto recorded from this state. These four were all common 

 at Saranac Inn, excepting the typical T. cynosura. So common 

 were they, in fact, that I stumbled on two desirable bits of information 

 concerning the genus that I should probably have missed had they not 

 been very common. The first of these relates to the proportionate 

 abundance of the sexes. Males mainly are collected by the ordinary 

 methods ; and for half a century or more students of the group have been 

 remarking on the striking preponderance of males in this and other 

 genera. 1 collected on Blueberry island in Little Clear pond in about 



10 minutes in cast skins of T. spin ig era and T. s em i a qu e a, 

 intermixed, taking them as they came, without any selection whatever. 

 These were separated as to species and sexes (the males being easily 

 recognized by the indications of the secondary genitalia on the ventral side 

 of the second abdominal segment) and counted, with the following results : 

 T. spinigera, ^S22, ?S24; T. semiaquea, Ss 25, $340, 

 in both cases a slight excess of females. I once counted a large number 

 of skins ofT. cynosura, and E. princeps taken from Purington 

 lake at Galesburg 111. I have not the figures resulting from the count, 

 but I remember distinctly that there was in each case a slight excess of 

 females. The females are more shy and seclusive, and therefore less 

 often taken. My breedings have never revealed any material excess in 

 numbers of either sex for any species; and these are certainly more reli- 

 able than chance captures in air. 



An acquaintance with the eggs of Tetragoneuria was likewise 

 almost forced on me. These are laid in strings, attached together in 

 masses (as shown in fig. 19) and hung on partly submerged twigs at the 

 surface of the water. These were very common objects about the shores 

 of Little Clear pond. I did not see any of them laid. That they belong 



