September 1S93.] 



PSYCHE. 



511 



ON VARIATION IN THE VENATION OF AN ARCTIAN WITH 

 NOTES ON OTHER ALLIED GENERA. 



BY HARRISON G. DYAR, BOSTON, MASS. 



In examining the venation of Pyr- 

 rharctia Isabella, I found a consider- 

 able range of variation. Seventeen 

 specimens were examined and they 

 varied in the following manner. In 

 thirteen of them, vein 10 of primaries 

 arose from the stalk which bears veins 

 7-9, at a variable distance from its 

 origin (see pi. 19, fig. 3 a and g). 

 This is to be considered the normal 

 venation. In one specimen vein 10 

 arose from the subcostal vein on the 

 discal cell (fig. 3_/"), and in two others 

 it arose from a stalk with vein n. 

 In one of these latter, the stalk arose 

 from the subcostal vein (fig. 3 c) and 

 in the other from the stalk which bears 

 veins 7-9 (fig $b). The latter speci- 

 men was further abnormal in lacking 

 veins 4 and 5 of the primary of one 

 side. Another variation is shown in 

 fig. 3 a and b, in which either veins 7 

 and S or S and 9 are on a common 

 stalk, that is to say in one case vein 9 

 is given off before 7, and in the other, 

 7 before 9. A slight variation in the 

 secondaries is shown in fig. 3 d and e, 

 where veins 3 and 4 are either fused 

 or w T ell separated at origin. 



There is here a sufficient range of 

 variation among the subcostal venules 

 to found four genera upon. Moreover, 

 it is probable that other genera may 

 vary as much, so that it would be well 



to consider this possibility in using such 

 tables of genera as that by Prof. Smith 

 in Can. ent.. xxii, 233, where the origin 

 of vein 10 is used as an important 

 character. While speaking of this 

 table, I will mention that the genera 

 Eupseudosoma, Nelphe and Ectypia 

 are wrongly placed. The former lacks 

 veins 5 and S of secondaries ; the 

 second also lacks vein 8 of secondaries 

 and has veins 7-10 of primaries on a 

 stalk ; the third genus has an accessory 

 cell, and should have been placed with 

 Nemeophila. Prof. Smith states that 

 two of these genera are placed by 

 him partly by guess, as indeed seems 

 evident. 



Genus Spilosoma Steph. This 

 genus differs from the new genera 

 Neoarctia and Elpis recently estab- 

 lished by Mr. Neumoegen and mvself, 

 in the position of the ocelli. In Spi- 

 losoma they are situated close on the 

 margin of the eyes ; in the new genera 

 they are separated from the margin by 

 a considerable space. 



S. vestalis Pack. In specimens from 

 Oregon the apex of the fore wings is 

 more pointed and the outer margin 

 more oblique than in those from Cali- 

 fornia. The black spots, too, seem 

 less strongly marked, and I took sev- 

 eral specimens at Portland in which 

 the abdomen was quite immaculate. 



