170 HEMIPTERA-HOMOPTEBA. 
Subfam. ATHALIONINA. 
The position of this subfamily, which is here regarded as containing the genus 
Aithalion only, has given rise to much difference of opinion among authors, and has 
been very differently located *. Germar (Mag. der Ent. iv. p. 94) places 4ithalion 
between Hupelix and Cicada; Amyot and Serville (Hist. Nat. Ins. Hémipt. p. 556) 
place it under the Cicadellina of Burmeister, among the group Eurymelides, and 
Walker (List of Homopt. Ins. iii. p. 646) follows the same arrangement ; Stal (Kongl. 
Sv. Vet.-Ak. Handl. Band viii. 1, p. 49) includes it under his Centrotida, which, 
however, he regards as merely a subfamily of his Jassida; while Ashmead (Ent. 
Americana, v. p. 125) makes Athalion and Hurymela the types of separate subfamilies 
(AEthalionine and Eurymeline) of the Bythoscopide. 
Aithalion has evidently strong affinities towards Tolania, but differs from it in too 
great a degree to admit of being classed in the same subfamily with the latter genus, 
an arrangement adopted by Goding (Trans. Am. Ent. Soc. xix. p. 253), and, if it must be 
definitely located, it is, perhaps, most correctly placed near or among the Centrotine. 
At the same time it differs from the rest of the Membracide, and if included under 
that family it becomes almost impossible to give a definition that will comprise all its 
members, for it neither has a pronotal process nor a perpendicularly declivous meto- 
pidium; nor does it altogether agree with the Jasside, and still less with the 
Bythoscopide, under both of which it has been located, In fact, Athalion is plainly 
a transitional genus and as such must be regarded; as, however, its affinities seem, if 
anything, to lean towards the Membracide, it is perhaps the best plan to provisionally 
include it under that family, though there appears to be no reason why it should not 
be placed under a separate family. In all zoological classification there seems too 
great a tendency on the one hand to force transitional genera under fixed families, and 
on the other to limit too closely the formation of new families and groups. In nearly 
all cases the family or group at its extreme end must be subject to exceptions, and must 
be more or less elastic. Stal is much blamed in certain quarters for too often using the 
words “ plerumque,”. *‘ seepissime,” “‘ rarissime,” &c. to qualify his definitions ; perhaps 
this is true to a certain extent, but it is difficult to see how he could have done other- 
wise in the case of the Homoptera, in the present state of our knowledge, and 
considering the very small available material that has hitherto been got together by 
collectors. 
AETHALION, 
Aitalion, Latreille, Consid. génér. sur les Crust., Arachn. et Ins. p. 263 (1810). 
Aithalia, Germar, Mag. der Ent. iv. p. 94 (1821). 
* For this reason it was omitted from the key to the subfamilies of Membracide, anted, p. 3. 
