The _Peduncle_ is generally rather short, and, with the exception of _S. Peronii_, is covered with calcified scales. These scales are generally small, and placed symmetrically in close whorls, in an imbricated order, with each scale corresponding to the interspace between two scales in the whorls above and below. In _S. ornatum_, the scales are so wide, transversely, that there are only four in each whorl. In _S. villosum_, the scales are spindle-shaped and arranged somewhat irregularly in transverse rows, not very near to each other. New calcareous scales originate only round the top of the peduncle, and they continue to grow only in the few upper whorls; and as the peduncle itself continues to increase in diameter by the formation of new inner membranous layers and the disintegration of the old outer layers, the calcareous scales come in the lower part of the peduncle to stand further and further apart. In the earliest stage of growth there are no calcareous scales on the peduncle in _S. vulgare_; they first appear under the carina. Spines are articulated in great numbers on the surface of the peduncle in _S. vulgare_, _S. Peronii_, and _S. villosum_, and very short ones on that of _S. rostratum_. _Attachment._--All the species, except _S. villosum_, are attached to horny corallines: the singular means of attachment in _S. vulgare_ will be described under that species, and is probably common to several of the other species. The larva in most, or in all cases, when it proceeds to attach itself, clings head downwards to the branch, and hence the capitulum comes to be placed upwards, with its orifice fronting the branch and the carina outwards. The sucking disc of the prehensile antennæ of the larva, in the five species examined, was a little pointed, and in shape resembled the hinder hoof of a mule: this may perhaps be accounted for by the narrowness of the branches of the corallines, to which it has to adhere: a large circular disc, as in Lepas, would have been worse than useless: the ultimate segment in most or all the species, has on its inner side (the segment being supposed to be extended straight forward) a notch or step, bearing, I believe, two spines. _Size and Colour._--Some of the species attain a medium size, others are small. The valves are generally clouded red or pink, but sometimes white.