370 PROCEEDINGS OF THE ACADEMY OF 



except the oblique basal subcostal one which is quite coarse, so very fine as to 

 be almost imperceptible to the naked eye, giviDg the whole wing a very peculiar 

 appearance. The anterior $ tarsus is very long ; in the living insect the first 

 joint is seen to be freely moveable. 



The 9 has two diverging carinse between the ocelli, the anterior and lateral 

 edges of the vertex, and sometimes its medial carina, and on each side two ab- 

 breviated vittae, yellowish. The markings of the abdomen are occasionally in- 

 distinct. 



Length J 1 10J 12 mill. ; 9 10 111 m ;n. Alar exp. $ 2330 mill. ; $ 

 26-32 mill. Length ^ seta 19-31 mill. ; $ 18-19 mill. Length $ ant. leg 

 (one specimen) 16 mill. Ant. tarsus 9 mill. ; 9 ant - ' e g (same size) 8 mill. 

 Described from fifteen <^, six 9- Say states that the wings are "whitish," 

 or" hyaline with a whitish reflection." In other respects his description agrees 

 with the 9 of the above. Very abundant at Rock Island, and I have also 

 taken it on Coal Valley Creek, Rock Island Co. and the Des Plaines River near 

 Chicago. 



The (J 1 and 9 subimago, with which Say was notacqua nted, differ from the 

 imago in the colors and markings being darker and more obscure, and in the 

 wings being fumose and the veins and cross-veins coarser and more distinct. 

 The tips of the hind wings, including the neivures, are pale greenish. As in all 

 other subimagos known to me, the posterior edge of the wings, when held up 

 to the light, exhibits under a strong lens a ciliated appearance, and the setae are 

 pilose. The $ anterior legs are no longer than those of 9- 



Length tf 11 mill. ; 9 1012 mill. Alar exp. J 1 29 mill.; 9 2930 mill. 

 Seta (J 1 13 mill. ; 9 14 15 m ^- Length ant. tf leg 8 mill ; it tarsus 4 mill. 

 One J, two 9- 



\\Batis. Subgenus B. First tarsal joint large, always larger than any of the 



three following; in anterior $ and 9 legs free, distinct ; in 4 posterior $ and 



9 lej-.s connate, indistinct; joints 1 4 regularly and moderately diminishing 



in length ; no difference in the relative proportions of $ an 'l 9 anterior tarsal 



joints. A rudimental intermediate seta, sometimes turned downwards. 



B;etis arida? Say. $ Ferruginous. Head light ferruginous; ocelli not 

 approximate, subequal ; a large black spot on the inside orbit of each posterior 

 ocellus, and a small spot on the back part of the front one; eyes in the dried 

 specimen black, occasionally with a broad interior pale purple vitta ; seta pale 

 at tip, sometimes entirely pale. Thorax and abdomen piceous above, except 

 the last abdominal segment, with ferruginous semicircles or triangles on the 

 basal half of each piceous segment of the abdomen ; longitudinal middle of 

 sternum and venter piceous ; seta pale greenish; anal appendages sometimes 

 fuscous towards the tip. Anterior legs long, obscure greenish, fuscous on the 

 terminal half of the femora and the tibial and tarsal tips, occasionally entirely 

 fuscous, except the basal half of the tarsal joints; four hind legs greenish 

 white, a little cloudy at the tips of the tarsi; the first tarsal joint in the an- 

 terior leg is free in the living insect. Wings hyaline ; veins and cross-veins 

 subequal, rather fine, greenish-hyaline, with a trace of fuscous at the extreme 

 base of the costa. 



The 9 differs from the $ as follows : The eyes of the living specimen are 

 ferruginous, with a broad yellowish vitta dividing them into two equal por- 

 tions, in the dead specimen dark ferruginous ; the vertex is yellow, sometimes 

 with a ferruginous vitta. Except in two specimens, where the markings are 

 similar to those of (J 1 , the body is of a nearly uniform ferruginous color ; the 

 anterior legs are generally marked as in the exceptional tf specimen ; and the 

 nervures of the wings, except, occasionally on the posterior margin of the front 

 wings, are pale fuscous. Similar sexual variations in the color of the wing 

 veins occur in Palingenia. 



Length J 1012 mill.; 9 913 mill. Alar exp. $ 22j 25^ mill. 



[Sept. 



