72 Mr. T. H. Withers on 
valves adjoining the carinal latus. Adopting Darwin’s idea 
as to the identity of the other valves, Thomson suggested 
that these linear valves must represent two elements of a 
carina. An alternative suggestion was that if the capi- 
tulum was reversed the linear valve would be a reduced 
scutum, the second latus a rostral latus, the first latus an 
upper latus, and the scutum a carinal latus. This latter 
view was suggested as possible, but further reasons were 
given for his inclination to follow Darwin’s ideas as to the 
identity of the valves. 
Wyville Thomson’s views have had no bearing on later 
discussions, for his paper has been entirely overlooked, and 
consequently his discovery of the split carina has passed 
unnoticed. It was only through a book-seller’s catalogue 
that I came across the paper myself, and I then found that 
the discovery of the split carina in the genus, as now found 
in the species S. pulchellum and S. haworthi, was not a new 
one. 
Except that later authors have differed as to the 
number of valves in the capitulum and as to the precise 
names of the first or upper latus and the second or carinal 
latus, Darwin’s purely tentative nomenclature has been 
generally accepted without question. So far has this been 
the case that no one has attempted to prove the identity of 
either of the valves. Any doubts, however, are set at rest 
by the new example of S. haworthi (PI. IV. fig. 2), for 
jn that specimen the valve called the scutum has its inner 
surface exposed, showing the pit for the adductor muscle, 
thus proving that this really is the scutum. 
Accepting this, it follows that the other valves would 
represent the upper latus, tergum, and carinal latus, and 
that the two linear valves would equal the carina of other 
cirripedes. Consequently the known valves would number 
ten in all. This is the same number as given by Darwin 
in his restoration, although the number is made up of 
different elements, for, apart from the carina being split, 
he included a rostrum. In none of the known specimens 
has a rostrum been noticed, and in view of the structure of 
the carina the improbability of a rostrum in the ordinary 
sense being present is great. There does not appear to be 
any differentiation in structure of the uppermost subscutal 
plates of the peduncle, and since they cannot be regarded as 
part of the capitular region, a rostrum or valves homologous 
with it cannot be said to form part of the capitulum of 
Stramentum. 
