From B. D. Walsh   1 May 1868

My dear Sir,

I have just received your letter of April 13^th.. I am very glad that the few scraps of information I have been able to give you have been of some service.¹

I write now because a case of apparent Sexual Selection in a genus of Butterflies has occurred to me, of which perhaps you will like to learn the details.

You probably are familiar with the common “Orange-tip Butterfly” (Anthocaris (mancipium) cardamines); & are aware that the males have a very conspicuous orange tip at the tip of the upper surface of the front wing, of which orange tip the female is entirely destitute. We have in the Atlantic States a species (Anthocaris genutia Fabr.), ranging from New York to Maryland, where the sexes differ in precisely the same manner. I have it ♂ ♀, but it is not found in Illinois.

In Anthocaris sara Boisduval (a California species) the male has just such an orange tip as the males of the other two species except that it is edged internally with black & is rather of a redlead color than orange.; but in the females it is said to be “paler than in the males, not edged with black, & divided at the extremity by a series of sulphury white marginal points.” I possess ♂; ♀ I do not personally know.²

In another California species, which is considered rare & which I do not possess in either sex, (Anthocaris lanceolata Boisd.)³ both sexes are said to be destitute of any orange or yellow or yellowish tip to the front wing. This species is only a little larger than the Atlantic species (A. genutia) & appears to be its representative. (Expanse 1$\frac{1}{8}$ inch). A. sara is as large as A. cardamines.

There are two other N. A. species of Anthocaris. 1^st. Anth. creusa Doubl. from the Rocky Mountains (Doubleday & Hewitson’s genera of Diurnal Lepidoptera, London, plate VII, fig. 1) which I know nothing about, & 2^nd. Anth. ausonioides Edwards, (formerly supposed by Boisduval to be identical with the European Anth. ausonia,) from California, the Rocky Mountains & Russian America. In this species, as well as in the European ausonia, (& apparently also in the European Anth. Tagis & A. Simplonia) both sexes are destitute of any orange tip.⁴

In this genus, therefore, we have the following gradations, the first of which, being the most numerously represented, may be considered as the primordial or normal form;

A. Both sexes without any orange tip. Ausonia, Tagis & Simplonia (Europe); Ausonioides & lanceolata (N. A.)

B. Male only with an orange tip. Cardamines (Europe); genutia (N. A.)

C. Male with an orange-red tip; female with the tip paler. Sara (N. A.)

(Anth. creusa Doubleday (N. A) locus incertus.)

I infer that in B the orange tip has been acquired by Sexual Selection, & that in C, this peculiarity of ♂, having been very long & very firmly established, is beginning by inheritance to appear in ♀ also.⁵ In confirmation of this theory, it may be remarked that in Sara ♂ the orange-red tip appears on both surfaces of the front wing, whereas in genutia ♂ & (unless my memory fails me) in cardamines ♂ also, it is orange & is confined to the upper surface. Whether it is so in Sara ♀, is not quite clear from the only description I have (that of Morris);⁶ but I rather infer that it is not, but appears, only much paler, on the lower surface as well as on the upper surface, in that sex.

Bates, in his Paper on the Lepid. Amazon Valley, shows how by simple variation in one & the same species (Leptalis Theonöe), & belonging too to the same family as Anthocaris, the tip of the upper surface of the front wing changes gradually from white to red (p. 565. Plate LV. figs. 9, 6, 4, 8, 5, 7. Plate LVI. figs. 3, 2, 1.)⁷

It is remarkable, as illustrative of what I have called “Unity of Coloration”,⁸ how very generally in Butterflies which have the tip of the front wing prolonged in a kind of triangle, that triangular space is occupied by white or by red spots, or by spots partly red partly white. You will see this in most of the Vanessa, especially in Atalanta & cardui & several species closely allied to the latter; in Danais archippus & Berenice & in Limenitis disippus & L. artemis. But it is more especially remarkable in Libythea motya, & in an undescribed(?) species of Apatura in my collection.⁹

In all the above-named Anthocaris, so far as I am aware, the under surface of the hind wing is marbled in a very peculiar & characteristic manner, with more or less tendency for the marbling to separate into 2 or 3 jagged transverse bands. In the arctic or subarctic genus chionobas (Hipparchia family)¹⁰ the same surface is marbled in almost exactly the same style, except that nature paints here with brown instead of green; &, instead of being subobsolete, the jagged transverse bands are very strongly pronounced. Here we have “Colorational Unity” again.

I sent you a Copy of my “Report” a few days ago. There is scarcely anything in it that will interest you, except that I have been presumptuous enough to criticize you on pp. 65–66.¹¹ I have been anxiously expecting your Book; but it has not yet come to hand. I wrote to Baillière long ago, to ask him to forward it to me by Express as soon as he received it.¹²

The “Practical Entomologist” was discontinued finally last October; but, as you will see, I have my hands full now as Acting State Entomologist, at all events until next winter.¹³ Entomology is rather looking upwards here in the Practical World. The State of Missouri has just appointed a young friend of mine, C. V. Riley¹⁴ of Chicago, State Entomologist with a salary of $2500 per annum. He is comparatively only a beginner in the science, but he is a hard-working intelligent young fellow, understands German which I am ashamed to say I do not, & though a very poor classical scholar like the most of his countrymen, has the stuff in him to be eventually very useful in his special line. I don’t know what is the reason, but neither France for the last hundred years, nor America since she was originally colonized, has ever produced one single good Greek Scholar.

“Darwinism” is now becoming quite a common creed in the United States, especially among the Entomologists; but I see that Agassiz¹⁵ is as inveterate as ever against it. Still, he is not ὁ πανύ now,¹⁶ as he used to be, even in New England; for several New England men have been lately led astray by the great heresiarch of Bromley.

Yours ever very truly, | Benj. D. Walsh

P.S. I mentioned in my last a horny black mark found in hind wing of our common ♂ Danais. Bates says this occurs in all ♂ Danais. (p. 502)¹⁷