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 S. quadratum and fosmla, five-sided, with the umbo at the upper 

 angle : in the eocene 8. quadratum, 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. Infra-median latera unknown ; they probably existed only in 8. magnum. Carinal 

 latera, known in 8. 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. quadratum ; but they probably existed in all : the naked peduncle, how- 

 ever, of the recent 8. Peronii must make us cautious on this head. 



\_A\ Valvce quatuordecem : Carina umbone sub-centrali. 



1. SCALPELLUM MAGNUM.^ Tab. I, Fig. 1. 



8. Laterum carinalium et rosfralium umbonibus libere {sicut cornua) prominentibus, 

 dimidiam. seu tertiam partem longitudinis valvarum cBquantibus. 



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 8calpellum 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 8. magnum was only a variety of 8. vulgare. The valves of 8. magnum 

 are all thicker, stronger, more rugged, and considerably larger than in 8. vulgare. Taking 



1 I 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. 



