Catalogue of the Odonata of Ohio. 



107 



middle of the second abdominal ring : in fact, so far as the head, 

 thorax, wings and length of femora are concerned, it might, with 

 propriety, be referred to Hagenius ; on the other hand the dilatation 

 of 7, 8 and 9, as well as the form of the anal appendages are strictly 

 in accord with Gomphus. The abdomen measures 50 mm. and the 

 hind wing 40 mm. Comparison with Hagen's and Selys' descriptions 

 of dilatatus discloses very close agreement except, of course, the 

 crossed triangles. There are slight variations, however, for example, 

 the lateral expansion of 8 has the anterior half yellow and there is a 

 small tooth beneath, at the beginning of the oblique truncation of the 

 superior appendages. (This is not mentioned in the descriptions) ; 

 the dorsal band includes 7 ; the membranule is white and the 

 pterostigma yellow. More material will be earnestly sought for when 

 May returns. 



76. — GOMPHUS EXTERNUS SelyS. 



One male captured — others seen — at Sugar Grove, May 18, 1895. 



The male has a peculiarity of flight which I do not remember to 

 have seen in any other Gomphid. Those observed were resting along 

 a sunny, sheltered roadway and when disturbed they would fly back 

 and forth, rising and falling in curves after the manner of a May-fly 

 in its love-flight. 



77. — gomphus fraternus Say, var. WALSHII. 



I have taken, in May and June along the Olentangy river at 

 Delaware and Columbus, several examples of Gomphus, which I am 

 led to think represent the form or variety of fraternus which Mr. B. 

 D. Walsh referred to in his accurate notes on this species,* and which 

 he said varied from the usual form by a yellow vitta on 9. The 

 variety, as I think it may with propriety be regarded, is easily 

 separated from the normal type by differences as follows: 1 — The 

 wide yellow vitta on 9 referred to by Walsh; 2 — The males of the 

 variety are larger : the length of abdomen (average of several) is 40 

 mm. and hind wing 31 mm. in the variety ; in the other the same 

 parts are 37 mm. and 29 mm. respectively; 3 — The occiput of the 

 variety is straight or even a little concave in some, while in fraternus 

 it is decidedly convex; the tenth ring has a dorsal, mesal yellow line; 

 there is a small tubercle near the tip of the superior anal appendages 



^Proceedings Ent. Soc. of Phila., vol., II, 240. 



