494 T. H. Withers — A new Cirripede from Chalk Marl. 



IV. A NEW ClRRIPEDE FUOM THE CeNOMANIAN ChALK MaRL OF 



Cambridge. 

 By Thomas H. Withers, F.G.S. 



OF the Cirripedes obtained by the late Mr. F. Mockler from the 

 Chalk Marl of Cambridge, two species, Zeugmatolepas mocMeri, 

 Withers, and Calantica {Titmiolepas) tuherculata, Darwin, sp., have 

 already been described and restorations given.' The remaining 

 material consists entirely of disconnected valves, and among these are 



(1) a number of valves referable to Pollicipes glaher, F. A. Roemer ; 



(2) a few valves of P. rigidus,'^ J. (ie C. Sowerby, together 

 with some valves of a new species^ which is probably related to 

 P. rigidus ; (3) an important series of valves belonging to several 

 species of Scalpellum allied to S. arcuatum, Darwin, and S.fossula, 

 Darwin ; and (4) some valves that do not belong to any of the species 

 already mentioned, and wliich it will be convenient to describe here. 



Included in this last series are three minute carinse and eleven 

 scuta (seven left and four right). I have also a single carina from 

 the Chalk Marl of Burham, Kent, and two scuta (left and right) from 

 the Cambridge Greensand of Cambridge, and these are all precisely 

 similar to the valves from the Chalk Marl of Cambridge. Except for 

 the fact that these carinas and scuta agree in having their outer 

 surface smooth, and that they were found with a considerable number 

 of valves of other species to which they do not belong, there is no 

 evidence to show that they represent a single species. I am inclined 

 to think that they do, but since they may belong to more than one 

 species, it will be best if we regard the carina as typifying the 

 species. It is noticeable that there are no terga among the valves, 

 but if the terga happened to resemble closely those oi^ Zeugmatolepas 

 mockleri, which present considerable variation, there would be some 

 difficulty in separating them. In point of fact, I have attempted to 

 sort out a few valves from the large series of terga of Z. mockleri, 

 but, while 07ie could figure extreme valves as belonging to another 

 species, one finds that they grade into other valves, and I have given 

 up the attempt. 



The carinse, of which two from the Chalk Marl of Cambridge have 

 been referred to by me (Proc. Zool. Soc. London, 1912, p. 531), 

 represent the second species to be described from British Cretaceous 

 rocks in which the umbo is in a sub-central position. Previously 

 described Cretaceous species of Scalpelhim with this advanced type of 

 carina come from the Upper Senonian, so that the occurrence of a similar 

 form so low down as the Cenomanian is especially interesting. I had, 

 however, overlooked the fact that Darwin had already recorded, but 

 not described, a carina from the Cretaceous of England with the 

 umbo in a sub-central position. At the end of his description of the 

 Tertiary Scalpellum magnum he says (1851, Pal. Soc. Mon. Foss. 

 Lepadidse, p. 21): "I may take this opportunity of stating, that 



^ Proc. Zool. Soc. London, December, 1913, pp. 937-48, pis. xciv, xcv. 



'^ Ann. Mag. Nat. Hist., ser. viii, vol. xiv, p. 171, pi. viii, fig. 4, August, 1914. 



3 Tom. cit,, p. 187, pi. viii, figs. 7-10. 



