Thanks LA and sends thanks to A. A. Gould for specimens. Describes principal findings of his research on cirripedes. Is obliged for information Joseph Leidy gave about cirripede eyes. Describes anatomical features and chief aspects of growth. Describes discovery of parasitic males and a species parasitic upon other cirripedes.
Down Farnborough | Kent
Oct. 22. 1848
My dear Sir
Although I have not yet received the Box with the Cirripedia, I cannot wait longer to
send you & D
The Cirripedia are true Crustacea with no affinities to other classes; M. St.
Ange curiously mistook a strong epithelium for an inner sort
of stomach, & hence the affinity with the Annelides disappears. The Cirripedia
are either a sub-class equal to the Siphonostomous & Maxillated classes
&c or to all these classes together; this I cannot decide yet. All cirripedes (except one forming an abnormal order) in their first larval
stage, have 3 pair of legs & two pair of antennæ in process
of formation within cases, & one eye: in the last stage, all have six legs, two
compound, not pedunculated, most singular eyes & a pair of prehensile
antennæ. In this stage they are pupæ, for they have no
mouth. In assuming the mature form, the compound eyes are moulted, & by the
act of moulting (by a process which I cannot explain without diagrams) the cirripede
assumes the position which it always holds, which is at right angles to that which the
pupa assumed when first attached. I am particularly obliged for the information about
The means by which Cirripedes are attached is one of the most remarkable parts of their Natural History: a portion of the ovarian cæca, becomes modified & glandular & secretes a cement, which is poured out by 2 ducts opening at the penultimate segment of the antennæ of the pupa, & fixing them permanently to the support. Afterwards the cement in some families is poured out by symmetrical orifices round the base of shell or peduncle, or in a single line, when the cirripede is attached to a coralline.— When the pupa moults, the whole of its envelopes are moulted, except the cemented antennæ: hence by care (& extreme care is requisite) the antennæ of the pupa can be demonstrated in the exact centre of the base of the largest Balanus or Anatifera.—
Strange as it may appear, this curious means of attachment is the only character absolutely universal in the Cirripedia, (some Cirripedia are apodal ).— I have made out, I believe with certainty from dissection & not from analogies the homologies of the cirripedia The shell, including the peduncle of the Pedunculata, consists of the 3 anterior segments of the head, so enlarged as to receive the whole rest of body, which consists of 14 segments in the larva & in some abnormal cirripedia (the cirri answer to the 5 pair of ambulatory legs & the outer pied-machoire of the higher crustacea), the 4 posterior abdominal segments being always aborted.—
The great majority of cirripedes are bisexual, but it seems that they can fecundate each other, for I have scrupulously examined a Balanus, which had had its penis cut off & was imperforate, but in which the ova were impregnated. I have one genus, in which the sexes are distinct, the male (sometimes two of them) being parasitic & permanently attached within the so-called sack of the female.— There is, however, one much stranger case, but of the accuracy of which I am positive after repeated dissections: the normal form is bisexual, but the male organs are small, though perfect & containing zoosperms, to make up for this, some of the pupæ, become attached to the orifice of the sack of the hermaphrodite, undergo a retrograde metamorphosis, never acquire a mouth or stomach, & are filled with testes, & ultimately the whole animal consists of a great sperm-receptacle full of zoosperms. As soon as these are discharged, these embryonic “supplemental males” die & are soon succeeded by another set: I have counted 10 of these supplemental males on one hermaphrodite. You will laugh at this account, but I assure you I would not presume to tell you anything, of which I was not sure, from repeated examinations of specimens taken at different periods & from different countries.—
The most remarkable individual cirripede, which I have seen is naked, apodal,
with a suctorial mouth, & parasitic in a double way within another
cirripede.— I hope I have not wearied you much
with these details: I sh
With sincere respect & my cordial thanks for your & D
I do not suppose I shall finish my Monograph for two or three years— my health allows me to work very little
- f1 1205.f1CD was actually in Shrewsbury from 10 to 25 October, his last visit before the death of his father (‘Journal’; Correspondence vol. 4, Appendix I).
- f2 1205.f2See letter to A. A. Gould, 3 September .
- f3 1205.f3See letter to J. E. Gray, 18 December 1847, n. 5.
- f4 1205.f4John Amory Lowell, who, as trustee of the Lowell Institute, Boston, invited Louis Agassiz, upon the recommendation of Charles Lyell, to deliver a course of public lectures at the institute in 1846. The great popularity of these lectures, on the ‘Plan of Creation in the Animal Kingdom’, was the main reason Agassiz decided to remain in the United States (Lurie 1960, pp. 116–33).
- f5 1205.f5Gaspard Joseph Martin-Saint-Ange. CD repeated this point in Living Cirripedia (1851) and frequently referred to Martin-Saint-Ange 1835.
- f6 1205.f6In Living Cirripedia (1854): 9–20, CD discussed the taxonomic rank of cirripedes, stating his belief that they should be considered as a subclass of the class Crustacea and describing the various relations that cirripedes hold to other divisions of Crustacea.
- f7 1205.f7Joseph Leidy had recently announced his discovery of eyes in a mature Balanus (Leidy 1848). CD mentioned this in Living Cirripedia (1851): 49.
- f8 1205.f8See Living Cirripedia (1851): 15, 52, and Living Cirripedia (1854): 95, 113.
- f9 1205.f9CD often repeated this statement (see Living Cirripedia (1851): 37). The anatomical correspondence between what he took to be the cement glands and the ovarian tubes suggested to him a homology between the two systems. In Living Cirripedia (1854): 151–2, CD speculated ‘that Cirripedes were once separated by scarcely sensible intervals from some other, now unknown, Crustaceans … with their oviducts opening at or near their second pair of antennæ’, and suggested how the ovaria could have been transformed into a cementing apparatus. This view was challenged in 1859 by August Krohn (Krohn 1859) (see letter from CD to Charles Lyell, 28 [September 1860], LL 2: 345, Calendar no. 2931).
- f10 1205.f10The name ‘cirripede’ is derived from the Latin for ‘curl’ (‘cirrus’) and for ‘foot’ (‘pes, ped-’) and ‘refers to the appearance of the legs, which can be protruded like a curled lock of hair from between the valves’ (OED). CD had a single specimen of what he took to be an aberrant cirripede completely lacking feet. He named the specimen Proteolepas bivincta and, using the feet as the character on which he based his orders, made it the sole member of the order Apoda.
- f11 1205.f11See letter to J. D. Hooker, 6 October , n. 12.
- f12 1205.f12See letter to J. S. Henslow, [1 April 1848], n. 6, for CD's use of the term ‘bisexual’ to mean hermaphrodite.
- f13 1205.f13This is probably the ‘fortunate chance’ that enabled CD to show that hermaphrodites fertilise each other and to which he referred in Natural selection, p. 45, and Origin, p. 101.
- f14 1205.f14Ibla cumingii (Living Cirripedia (1851): 183–203), first mentioned in letter to J. S. Henslow, [1 April 1848].
- f15 1205.f15The genus Scalpellum (see letter to J. D. Hooker, 10 May 1848, n. 12).
- f16 1205.f16Proteolepas bivincta (see n. 10, above).