18 FOSSIL CIRRIPEDIA. 
Rostrum unknown in any fossil species; but judging from recent species, it probably 
existed in all. 
Upper latera known only in three species; in S. magnum it is irregularly oval, with 
the umbo central: in 8. guadratum and fossula, five-sided, with the umbo at the upper 
angle: in the eocene S. guadratum, however, an inner ledge very slightly projects beyond 
the two upper sides, and first indicates a tendency to upward growth.  Rostral latera, 
known only in S. magnum and quadratum, they are transversely elongated, narrow, and 
small. nfra-median latera unknown ; they probably existed only in S. magnum. Carinal 
latera, known in S. magnum, quadratum, fossula, solidulum, and maximum ; in the first species 
they are transversely elongated ; in the three latter, of an irregular curved shape, and flat. 
In the fossil and recent species, the rostral and carinal latera grow chiefly in a direction 
towards each other ; so that their umbones are close to, or even seated exteriorly to, the 
carinal and rostral ends of the capitulum. Peduncle, calcified scales are known only in 
one species, the 8. guadratum ; but they probably existed in all: the naked peduncle, how- 
ever, of the recent S. Peronii must make us cautious on this head. 
[A] Valve quatuordecem: Carine umbone sub-centrali. 
1. Scatpentum maenum.' Tab. I, Fig. 1. : 
S. Laterum carinalium et rostralium umbonibus liberé (sicut cornua) prominentibus, 
dimidiam seu tertiam partem longitudinis valvarum equantibus. 
Carinal and rostral latera, with their umbones projecting freely like horns, and 
equalling one half or one third of the entire length of these valves. 
Coralline Crag (lower part). Sutton, Gedgrave, Sudbourne. Mus. S. Wood and Lyell. 
From the close affinity between this species and the recent Scalpellum vulgare, we 
may confidently infer that the capitulum consisted of fourteen valves, which are all pre- 
served in Mr. Wood’s collection, with the exception of the infra-median latera and of 
the rostrum. This latter valve would, no doubt, be rudimentary, and it has been over- 
looked by naturalists even in the recent species. The chief difference, excepting size, 
between these two species, is in the form of the rostral and carinal latera, but unfortunately 
these valves are extremely variable. It might even be maintained, with some degree of 
probability, that S. magnum was only a variety of S. vulgare. The valves of 8. magnum 
are all thicker, stronger, more rugged, and considerably larger than in S. vulgare. Taking 
1 T have followed Mr. Morris in his Catalogue, in adopting this name from the MS. of Mr. Searles Wood, 
to whose kindness I am greatly indebted for having placed in my hands the whole of his large series of 
valves of this species. 

