386 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3 d Ser. 



15. Herpetogomphus elaps Selys. 



Plate XXV, Fig. 2. 



Erpetogomphus elaps Selys, Monog. Gomph., 1857, p. 70, PI. IV, fig. 4. 

 Herpetogomphus elaps Hagen, Proc. Bost. Soc. Nat. Hist., Vol. XVIII, 

 1875, p. 42; Kirby, Cat. Odon., 1890, p. 60. 



Although the hind margin of the occiput of this species 

 has been described as "straight," most of these specimens 

 show a tendency towards emargination in the middle, as is 

 actually shown in Monog. Gomph., PI. IV, fig. 4a. 



The female of elaps differs from that of viperinus chiefly 

 in the absence of the submedian thoracic, and the indistinct- 

 ness of the antehumeral bands, and by the vulvar lamina 

 being bilobed, the interval between the right and left lobes 

 being deep and semicircular and therefore bounded by 

 curved sides. 



The neurational details given for viperinus on the pre- 

 ceding page are equally true for elaps; the anal triangle of 

 the male is similarly formed and divided. 



Dimensions: Abdomen, S 33-35 mm., 2 31 mm.; hind wing, S 25-26 

 mm., 2 28.5 mm. 



6$ 1 ? Tepic, Oct., 1894, Eisen and Vaslit. 



73 1 $ " Nov., 1894, " 



133 2? 



The characters which Baron de Selys used in the latest 

 synopsis of the species of Herpetogomphus, 1 viz. : — 



A. Pterostigma black. Black patterns of the body well marked. H. 

 compositus, designatus, viperinus. 



B. Pterostigma brown or yellowish. Brown patterns of the body oblit- 

 erated in part. H. menetriesii, elaps, boa, cophias, crotalinus. 



seem to be of little value, judged by the two species of 

 Herpetogomphus here represented. In some individuals of 

 elaps the pterostigma is quite as black as in viperinus, and 

 the dark bands of the female viperinus are but little better 

 defined than in some individuals of elaps. Unfortunately, 

 after pointing out the defects of this grouping, I have noth- 

 ing to offer as a substitute, owing to insufficient materials. 



1 Coinptes Rendus Soc. Ent. Belg., 1879, p. lxiii. 



