44 GROTE—THE DESCENT OF THE PIERIDS. (Jan. 5, 
brought out in my writings, a comparison of these two types would 
remove it. Eurema represents a stage which MVaz¢hais has aban- 
doned in all the above particulars. 
Gen. Zerias Swainson, 1820. 
Type: T. hecabe. 
Terias hecabe. Grote, Proc. Am. Putt. Soc., Vol. xxxvil, Pl. 1, 
Fig. 6 (neuration). 
The wings are more ample, longer than in Awrema, but the 
neuration agrees so closely that I cannot precise any differences. - 
It has seemed to me, by infinitesimal points, as less specialized ; 
but it marks no new phase in the movements of the veins. The 
genus appears of very doubtful necessity and can be omitted from 
a table. 
Gen. Xanthidia Boisduval, 1829. 
Type: X. nicippe. 
Xanthidia nicippe. 
But if the necessity of Zeréas is doubtful, there seems too little 
for the retention of the present type, which agrees in the more 
ample wings with Zervzas. All the positions of the veins are main- 
tained. I find only a slight variation in the discal cross-veins ; on 
the hind wings of Xanthidia the latter run more obliquely outward 
superiorly, more continuously with d/2; on the fore wings, the 
inward bulging is slightly less pronounced. It seems a good deal 
like trifling to consider this a distinct genus and I can make no use 
of it. See Mr. Scudder’s remark, /. c., p. 288. Ihave been unable 
to secure a specimen of Ades cebrene for comparison. 
Gen. Sphenogona Butler, 1870. 
Type: S. bogotana. 
Sphenogona mexicana. 
I have neither dogotana, which Mr. Kirby considers type, nor 
ectriva, so given by Mr. Scudder. Mr. Kirby writes that dogofana 
- quite agrees with my species and I can readily believe it. The 
neuration is practically identical with that of Hurema or Tertas ; 
again the cross-vein of secondaries is a little less bulging, straighter. 
The only distinction upon which to found the use of a separate 
name, is that the hind wings are produced or angulate on external 
