16 FOSSIL CIRRIPEDIA. 
with straight spines, serving, apparently, to protect the entrance of the sack: the whole 
animal is attached, like ordinary cirripedes, first by the prehensile antenne, and afterwards 
by the cementing substance ; the whole animal may be said to consist of one great 
sperm-receptacle, charged with spermatazoa; as soon as these are discharged, the animal 
dies. 
A far more singular fact remains to be told : Scalpellum vulgare is like ordinary cirripedes, 
hermaphrodite, but the male organs are somewhat less developed than is usual; and, as 
if in compensation, several short-lived males are almost invariably attached on the occlu- 
dent margin of both Scuta, at a spot marked by a fold (not thus caused), as may be seen 
on the inside view of this valve in the fossil 8. magnum, which, in all probability, was 
furnished with them. I have called these beings complemental males, to signify that they 
are complemental to an hermaphrodite, and that they do not pair like ordinary males with 
simple females. In Scalpellum vulgare, the complemental male presents only slight specific 
differences from the male of 8. ornatum. It would be foreign to the purpose of this 
volume here to enter on further details; nor should I have touched on the subject, had I 
not wished specially to call attention to the presence of cavities on the under sides of the 
Scuta above the pits for the adductor muscle. I will only add, that in the other species of 
Scalpellum, the complemental males are more highly organised, and are furnished with a 
mouth and prehensile cirri; the valves are more or less rudimental in the different species ; 
these complemental males are not always present, and are never attached to young herma- 
phrodites ; when present, they adhere in such a position, that they can discharge their sper- 
matozoa into the sack of the hermaphrodite: their attachment does not affect the form of 
the valves.’ 
Description of Valves.—It will, I think, be most convenient to confine the following 
description to the fossil species of the genus. No one specimen has been found quite 
perfect ; but, judgmg from analogy, the capitulum was probably formed of fourteen valves 
in S. magnum, and of twelve in the remaining species. These valves are commonly smooth, 
1 Exactly analogous facts are presented, though more conspicuously, by the two species of the genus 
Ibla. Before examining this genus, I had noticed the complemental males on Scalpellum vulgare, but had 
not imagined even that they were Cirripedia. bla Cumingii (as I propose to call a new species collected by 
Mr. Cuming, at the Philippines) is bisexual; one or two males being parasitic near the bottom of the 
sack of the female. These males are small, are supported on a long peduncle, but are not enclosed in a 
capitulum (such protection being here unnecessary), are furnished with a mouth, ordinary trophi, stomach, 
and anus; there are only two pair of cirri, and these are distorted, useless and rudimentary; the whole 
thorax is extremely small; there is no penis, but a mere orifice beneath the anus for the emission of semen: 
hence Ila Cumingit is exactly analogous to Scalpellum ornatum. On the other hand, the closely allied 
Australian Ibla Cuvierii, like Scalpellum vulgare, is hermaphrodite, but has, in every specimen*epened by 
me, a complemental male attached to near the bottom of the sack; this complemental male differs only 
about as much from the male of Ié/a Cumingii, as the female J. Cumingii differs from the hermaphrodite form 
of I. Cuvierii. I intend hereafter to give detailed anatomical descriptions and drawings of the males and 
complemental males of Ibla and Scalpellum. 
