AMERICAN ODONATA. 213 



Gomphiis elongatus Selys. Syn. Goniph., p. 39 (or 58), 1854. In 

 Quatr. Add. Syn. Gomph., p. 60 (or 465), 1878, this species is an- 

 nounced as a synonym of plagiatus, and the previously expressed 

 opinions of Selys and Hagen that it was spiniceps or notatus are cor- 

 rected. Kirby (Syn. Cat.) places it again under notatus. It seems 

 t(j he plagiatus for several reasons: color of face; form of occiput; 

 the humeral stripe is not mentioned as being constricted above, as it 

 plainly is in notatus and spiniceps, being normally interrupted in the 

 latter; and the color of abdomen, as described in the Mon. Gomph., 

 p. 161 (or 421), "the color of the abdomen is almost entirely ob- 

 scure reddish," clearly indicates plagiatus, never being true, so far 

 as I know for iiotatus or spiniceps. 



GompJms plagiatus Selys. In Selys' descriptions of this species 

 in the Mon. Gomph., p. 159 (or 419), and the Syn. Gomph., p. 38 

 (or 57), the size is unusually small (ab. 40 ; h. w. 30), and the num- 

 ber of postcubitals (!S) in front wings is smaller than in any speci- 

 men I have examined. 



Gomphus olivaceous Selys. Trois. Add. Syn. Gomph., p. 21 (or 

 749), 1873. Hagen, Kept. U. S. Geol. Sur. Tei-r., p. 597, 1873. I 

 have" been unable to examine specimens of this species, which proba- 

 bly belongs in this subgenus. It is close to plagiatus, but is smaller, 

 and Hagen considered them two .species. 



The Postanal Cells in the Genus Gomphus. 

 Professor Needham has kindly called my attention to the fact that 

 the cells between the branches of the anal vein might ofter a taxo- 

 nomic character, and, with this idea in mind, in connection with the 

 study of the subgenus Stylurus, I have studied specimens of twenty- 

 six North American species and three European species of the genus 

 Gomphus. I have examined the specimens above mentioned of 

 Stylurus, the U. S. Nat. INIus. collection embracing 197 specimens in 

 addition to the specimens of Stylurus above listed, twenty-one speci- 

 mens of G fraternus, crassus and externus kindly loaned me by Mr. 

 Adams, and most of the specimens in my own collection — altogether 

 I have tabulated under Figs. 1-6, plate viii, 822 wings. A few 

 wings examined, because of their abnormal character, were not 

 tabulated. With one or two exceptions, these abnormal wings 

 belonged to G. brevis. Fig. 3«, pi. viii, is such a wing; it is the 

 only case observed where the po.stanal cells continue to the margin 

 of the wing as a single row. 



TRANS. A.M. ENT. SOC, XXVII. MAY, 1901. 



