32 FOSSIL CIRRIPEDIA. 
Lithotrya, and from what may be faintly seen in the tertiary Pollicipes carinatus, and even 
in some specimens of P. mztella, I believe that this structure indicates that the upper freely 
projecting portion of the carma had its inside filled up and rendered prominent, which we 
shall see is the case with the carina of the variety cylindraceum. Length of largest 
specimen, eight tenths of an inch. 
This variety is found at Norwich, in Scania, and at Cyply bei Mons, in Belgium. 
Amongst the Scanian specimens from Kopinge (where the carina of the true S. mazi- 
mum is commonly found) there are some terga differing from the variety just described, 
only in having the lower part of the valve less produced; and more especially in having 
on the internal surface of the upper part a smooth prominent ridge, lying rather nearer to. 
the occludent than to the carmal margin, and therefore in exactly the same position in 
which a little group of small, sharp, longitudinal ridges occurs in the terga of S. arcuatum 
and of some other species. I am surprised at such a point being variable, but I cannot 
doubt that this valve belongs to the same species. I may add that it was this trifling 
point of structure, which first led me to suspect that these singular crescent-shaped 
valves were really terga. Finally, I may remark, that when all the ten terga now described 
are placed in a row, it is scarcely possible to doubt that they form merely varieties of the 
same species. 
Carinal latus, Tab. II, fig. 4. This is the only valve which remains to be described, 
for neither the rostrum nor rostral latera are as yet known. It was found at Kopinge, in 
Scania, where the carina of the true S. maximum occurs abundantly ; it was sent to me by 
Professor Steenstrup, who attributed it to this species. I have also seen a specimen from 
Hanover, where the carina of the true S. maximum is also found, and another small 
specimen from Charing, in Kent. Valve thin, of an irregular shape, sub-triangular ; flat, 
except at the umbo, which projects outwards, owing to a ledge formed beneath and round 
it; carinal margin very slightly convex, with a linear furrow parallel to it, between which and 
the edge the lines of growth are abruptly upturned; lower margin considerably convex ; 
upper margin slightly concave, with a slight depression parallel to it, between which and 
the edge the lines of growth are rectangularly reflexed towards the umbo. The two Scanian 
specimens differed slightly im outline ; chiefly with respect to the projection of the ledge 
round the umbo. Width of largest specimen one quarter of an inch. ‘This valve unmis- 
takeably resembles the homologous valves in S. quadratum and fossula, but can be 
distinguished from both; the end opposite the umbo is much less produced than in S. 
quadratum ; the whole valve is wider, and the furrows much less developed, than in 
S. fossula, to which it comes nearest. 
Affinities. Before describing the several varieties as characterised by their carinz, I will 
offer a few remarks on the affinities of this, the most common and widely distributed species 
of all the cretaceous pedunculated cirripedes. Mr. James Sowerby at first naturally 
described it as a Pollicipes; quite lately in Mr. Dixon’s work he has considered it as 
belonging to the same genus with his eocene Aiphidium quadratum and our Scalpellum 

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