Finally, the simple fact of the diversity in the sexual relations, displayed within the limits of the general Ibla and Scalpellum, appears to me eminently curious; we have (1st) a female, with a male (or rarely two) permanently attached to her, protected by her, and nourished by any minute animals which may enter her sack; (2d) a female, with successive pairs of short-lived males, destitute of mouth and stomach, inhabiting two pouches formed on the under sides of her valves; (3d) an hermaphrodite, with from one or two, up to five or six similar short-lived males without mouth or stomach, attached to one particular spot on each side of the orifice of the capitulum; and (4th) hermaphrodites, with occasionally one, two, or three males, capable of seizing and devouring their prey in the ordinary Cirripedial method, attached to two different parts of the capitulum, in both cases being protected by the closing of the scuta. As I am summing up the singularity of the phenomena here presented, I will allude to the marvellous assemblage of beings seen by me within the sack of an _Ibla quadrivalvis_,--namely, an old and young male, both minute, worm-like, destitute of a capitulum, with a great mouth, and rudimentary thorax and limbs, attached to each other and to the hermaphrodite, which latter is utterly different in appearance and structure; secondly, the four or five, free, boat-shaped larvæ, with their curious prehensile antennæ, two great compound eyes, no mouth, and six natatory legs; and lastly, several hundreds of the larvæ in their first stage of development, globular, with horn-shaped projections on their carapaces, minute single eyes, filiformed antennæ, probosciformed mouths, and only three pair of natatory legs; what diverse beings, with scarcely anything in common, and yet all belonging to the same species! [62] ‘Annals of Natural History,’ vol. ii, (2d series, 1848,) p. 153, Pl. vi. Mr. Dalrymple has published a very interesting paper on the same subject in the ‘Philosophical Transactions,’ (p. 342,) 1849; and there is another Memoir by Mr. Gosse in the ‘Annals of Natural History,’ vol. vi, (1850,) p. 18. _Genus_--POLLICIPES. Pl. VII. POLLICIES. _Leach._ Journal de Physique, tom. lxxxv, Julius, 1817.[63] LEPAS. _Linn._ Systema Naturæ, 1767. ANATIFA. _Brugière._ Encyclop. Méthod. (des Vers), 1789. MITELLA. _Oken._ Lehrbuch der Naturgeschichte, 1815. RAMPHIDIONA. _Schumacher._ Essai d’un Nouveau Syst. &c., 1817 (ante Julium). POLYLEPAS. _De Blainville._ Dict. des Sc. Nat., 1824. CAPITULUM (secundum Klein). _J. E. Gray._ Annals of Philos., tom. x, new series, Aug. 1825.