1919.] NATURAL SCIENCES OF PHILADELPHIA. 81 



H. ; on grassy benches of canyon slopes to tops of ridges and, very 

 rarely, in tall yellow grass in the zone of oaks); 6 cf, 4 9. 



Mermiria alacris Scudder.so PUte V, figs. 28 35; Plate II, figs. 1-4. 



1877. Mermiria alacris Scudder, Proc. Boston Soc. Nat. Hist., xix, p. 30. 

 [cf, 9 : Georgia.] 



1897. Mermiria rostrata McNeill, Proc. Davenp. Acad. Nat. Sci., vi, 

 pp. 205, 207, pi. I, fig. 3c. [cf, 9 : Mackay, Oklahoma (Indian Terri- 

 tory).] • . 



1899. Mermiria vigilans Scudder, Proc. Amer. Acad. Arts and Sci., xxxv, 

 pp. 42, 43. [(f', 9 : Smithville, North Carolina] 



Comparison with M. neo-mexicana, the only close ally of the 

 present species, has already been made under that form. 



This species was based on a series of thirty-two males and two 

 females, collected in "Georgia" by H. K. Morrison. Of these 

 we have exanwned nineteen males and one female, all in the Scud- 

 der Collection at the Museum of Comparative Zoology with the 

 exception of one male in the United States National Museum. 

 We here select a single male as the lectotj'pe. 



Single Type (by present selection). — d^ ; Georgia. ''Type speci- 

 men." " Mermiria alacris Scudd." [Scudder Collection in Museum 

 of Comparative Zoology.] 



Morphological Notes.- — The striking morphological variational 

 feature seen in this species is that most noticeable in the other 

 species of the genus, i. e. the form of the fastigium. This variation 

 is spread over the whole distribution of the species and not con- 

 fined to any one region or sex. In the more rounded tj'pe the 

 fastigium forms a rounded, approximately 70° (9) or 65° (d^) 

 angle, from which the variations range through all degrees of 

 production and rounding to 42° ( 9 ) or 33° (o^). The character 

 of the lateral margins of the fastigium varies independently of 

 the exact angle, being weakly arcuate to straight. The exact 

 outline of the dorsum of the head, when seen from the side, the 

 degree of decurving of the fasti gial line, the exact form of the 

 outline of the eye and the exact location of the fastigial impression 

 are all variable and, apparently, always individually. The eyes 

 show similar extremes of this variation to those occurring in inter- 

 texta, while the presence or absence of the weak fastigial medio- 



2" The immature material from Nugent, Mississippi, recorded by Morse as 

 Mermiria bivittata fCarneg. Inst. Wash. Publ., No. 68, p. 28, (1907)), repre- 

 sents, instead, the present species. The adult material there recorded is, how- 

 ever, true bivittata. It is highly probable that the immature specimens recorded 

 at the same time from Biloxi and Hattiesburg, Mississippi, also represent alacris, 

 as bivittata is, apparently, an earlier maturing species, but we have only imma- 

 ture material from Nugent, kindly loaned by Prof. Morse, before us. 



