^0 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



The members of the genus are apparently single brooded, judg- 

 ing from numerous collecting records, the adults usually occurring 

 in June and July. 



Key to Species. 



1. First sector branching so as to form five apical and three ante- 



apical cells 2 



First sector branching but forming only four apical and two ante- 

 apical cells distinctus 



2. Last ventral segment of female notched or concavely rounded but 



without projecting teeth either side of notch 3 



Last ventral segment notched, with projecting teeth more or less 

 pointed either side of notch 6 



3. Last ventral segment one-half longer than preceding, roundingly 



produced from base, deeply notched at apex 4 



Last ventral segment proportionately shorter, notch shallow 5 



4. Face very strongly convexly inflated, color above black shining, 



unmarked tumidif rons n. sp. 



Face moderately inflated, not bulbous, above pale or with pale 

 markings, clavus usually conspicuously marked variabilis 



5. Face black, notch broad and shallow giving segment a bilobed 



appearance nigrinasi 



Face usually bright yellow, female segment rounded, posterior 

 margin with small shallow notch sobrius 



6. Last ventral segment of female triangular, produced medially, 



apical teeth usually distinct 7 



Last ventral segment of female not medially produced, notch 

 almost obsolete, teeth often missing or very small cognatus 



7. Elytra dark, clouded, with whitish or hyaline areas 8 



Elytra hyaline, nervures brown, apex clouded; vertex dark, a 



broad yellow band connecting ocelli pruni 



8. Size large 4.5-5 mm., last ventral segment strongly produced medi- 



ally forming two large distinct teeth fitchi 



Size smaller, 4 mm., last ventral segment but slightly produced^ 

 medially, teeth short, rather distant minor 



O. variabilis (Fitch). Athysanus variabilis Fitch. Athysanus 

 abietis Fitch. Macropsis clitellarius Provancher. (Fig. 5, 

 5a, b.) 



Homop. N. Y. St. Cab., 60, 185 1. 



As the specific name indicates, a great variation in color is found 

 in a series of specimens. Often sulphur-yellow with an oblique 

 black line along claval suture. A common form on alder is rusty 

 brown with clavus pale yellow. Length 5 mm. 



Abundant on birch and alder. 



Branford, 5 July, 1904 (P. L. B.) ; North Branford, 8 June, 1912 

 Hamden, 30 June, 1913 (B. H. W.) ; New Haven, 17 June, 1904 (H. L. V.) 

 28 May, 1905, 14 July, 1909 (B. H. W.) ; Suffield, 21 May, 1917 (M. P. Z.) 

 Huntington, 9 July, 1920; Orange, 22 June, 1920, 17 July, 1920 (B. H. W.) 

 Cornwall, 5 June, 1921 (B. H. W.). 

 *0. tumidif rons DeLong, n. sp. (Fig. 6, 1-4.) 



Size and form of variabilis which it resembles, but from which 

 it differs by the greatly inflated face and its distinct coloration. 

 Length 4.5 mm. 



