374 Mr. T. H. Withers on the 
the rostral end of the capitulum, especially beneath such a 
large wide plate as the rostrum actually is, and in my 
opinion it is a subcarina, for which there is room between 
the carinal latera—otherwise there would be a_ hiatus 
between the incurved outer margins of these valves. 
The capitulum has therefore fifteen valves only of which 
there is any proof, and, in view of the large size of the lower 
latera, it is extremely unlikely that there were any more. 
Had there been more it is quite certain that fragments 
would have turned up in the large amount of material that 
I have examined, for several other specimens exhibit lower 
lateral valves and in some cases the peduucular plates. 
While Darwin thought that there were more than three 
pairs of lower lateral valves, he was of the opinion that there 
was only a single lower whorl, and, since it has now been 
shown that there could have been only three pairs of latera, 
there remains no justification, quite apart from other con- 
siderations, for the reference of this form, and by inference 
the related species, to the genus Pollicipes. A restoration 
is given of the capitulum, and except in the case of the 
rostrum and subcarina, the exact position of each valve is 
proved by one or other of the specimens discussed here. 
Evidence for this restoration is just as strong in the case 
of the allied species Pollicipes glaber from the Chalk Mar. 
Precisely similar valves to those known to comprise the 
capitulum of P. unguis have been found detached, including 
a great number of the peduncular plates, and the absence 
of any other type of valve, although negative evidence, is 
strong confirmation of the above conclusion. 
The structure of the capitulum of P. wnguis shows that it 
represents a type distinct from those already known, but, in 
deference to the views of certain eminent authorities on recent 
Cirripedes, I refrain from making it a distinct genus, and 
content myself with regarding it as a subgenus of the genus 
Scalpellum, s. sty., definable as below :— 
CRETISCALPELLUM, subgen. noy, 
Scalpellids with the upper whorl of valves as in the sub- 
genus Arcoscalpellum, except that the carina is simple (that 
is, not divided off into tectum, parietes, and intraparietes), 
and with three pairs of large practically undifferentiated 
lower lateral valves, of which the inframedian latus overlaps 
the rostral and carinal latus on either side ; rostrum excep- 
tionally large and wide; peduncular plates large with a 
smooth, narrow, inwardly-projecting basal ledge. 
Subgenotype.— Scalpellum (Cretiscalpellum) unguis (J. de 
C. Sowerby). 
