32 FOSSIL CIRRIPEDIA. 



Lithotrja, and from what may be faintly seen in the tertiary PoUicipes carinatus, and even 

 in some specimens of P. mitella, I believe that this structure indicates that the upper freely 

 projecting portion of the carina 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. maxi- 

 mum is commonly found) there are some terga difiering 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 carinal margin, and therefore in exactly the same position in 

 which a little group of small, sharp, longitudinal ridges occurs in the terga of S. arciiatum 

 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 difiered slightly in 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 carinse, I will 

 offer a few remarks on the aftinities of this, the most common and widely distributed species 

 of all the cretaceous pedunculated cirripedcs. Mr. James Sowerby at first naturally 

 described it as a PoUicipes ; quite lately in Mr. Dixon's work he has considered it as 

 belonging to the same genus with his eocene Xiphidium quadratum and our Scalpellum 



