40 
diagnosis in few words, of its frequent occurrence in the north and the 
consequent improbability of its having been unknown to Linne, of the 
characterisation of the larva, so far as it goes, and especially of the 
emphasis laid on the white, posteriorly red-yellow costal spot, which 
he considers Linne was very fortunate in selecting for a diagnostic 
mark. I may add that I have myself run through all the Scandinavian 
Geometridae, and find no others but C. truneata and immanata to which 
this would apply. It must be borne in mind that prior to 18G1 very 
few of the German entomologists even contemplated the possibility 
that these would turn out two different species. 
The further restriction of the name to immanata, Haw. ( — truneata, 
Wrnbg., pro parte), was, if I mistake not, first suggested by Staudinger 
in 1871 (Cat., ed. 2, p. 183), and made definitely by Wallengren in 
1874. In the latter author’s “ Index Specierum Noctuarum et 
Geometrarum in Scandinavia,” etc. (Bill. Seemah. Yet. Ah. Handl., ii., 
no. 4), on page 30 we find our two species cited under the following- 
synonymy : no. 129. — C. truneata, Iiufn. (russata, Tr., variata, Thbg.). 
no. 130. — C. citrata, Lin. (immanata, Haw.). 
The fact that no indication is given that this is new synonymy, 
may possibly point to the existence of an older reference which I have 
overlooked, but I do not think so. After careful consideration, I feel 
absolutely bound to accept it; not only because it is the oldest 
determination and cannot be proved erroneous, but also because — as I 
have already remarked—the choice seems to lie exclusively between 
these two allies, and Avith the balance of argument in favour of 
immanata, thus : 
(1) As a matter of fact, the “large whitish spot distally on the 
costal margin ” is much more conspicuous, as a rule, in immanata than 
in truneata. 
(2) Immanata is probably the commoner species in the north, hence 
the more likely to ha\-e been first noticed. 
(3) On grounds of convenience, inasmuch as the name citrata is 
older than either of the others, it is more satisfactory to supplant the 
younger name (immanata) by it; if it should then be proA'ed that, e.y., 
rufescens, Strom (1783), or striyulata, Fab. (1794), pertained to 
immanata, not to truneata, it would not in\'olve a still further change 
of specific name. 
I am at a loss to imagine on Avhat species of Citrus the larva had 
fed in Sweden, and it is ahvays possible that Kolander had bred it in 
some Eastern travels, and that its introduction into the SAvedish 
fauna Avas due to error, or oversight; but of this there is no shadow of 
evidence, and even if it were so, the easterly range of C. immanata is 
such as not to preclude the determination. Henceforth, then, I shall 
write of Cidaria (or Dysstroma) immanata as citrata, Linn. 
A complete chronological list of the names, specific and A T arietal, 
Avhich have to he dealt with under this group, will shoAV hoAV formidable 
is the task of getting them thoroughly into order. I append to each 
name an indication of Avhat, in my judgment, is its correct location, so 
that this list will form a sort of rough index to the notes AA'hich 
fo'loAv. 
1761.- — Phalaena (Geometra ) citrata, Linn., Faun. Suec., 2nd ed., 
p. 382. 
xviii. 
