ox FOSSIL CTRRTPEDrS. 937 



54. Cirripedes from the Cenomanian Chalk Marl of 

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



[Received September 25, 1913 : Read November 25, 1913.] 



(Plates XCIV. & XOV.t) 



Index. 



Page 



Structure of Zeuffviatolepas and Titanolepas 941, 946 



Lines of Evolution in Pollicipedidse 937 



Distribution (Geological), Cretaceous of Europe, Zeuffmato- 



lepas a,ud Calantica {Titanolepas) 939,944 



Zeugmatolepas mocMeri, gen. et sp. n 938 



.Z. <?rete Steenstrup sp 941 



ScalpeUum cretcB Steenstrup sp., referred to Zeugmatolepas . 942 



Zeugmatolepas conrpaved with PolHcipes 941 



ScalpeUum ticbercwlatum Darwin, referred to Titanolepas . 943 

 Titanolepas subgen. nov. of Calantica, for ScalpeUum 



tuhe^-ciilatum, DnYwhi 943 



Calantica, see Titanolepas and Scillcelepas 947 



S oil Icel epa s coinimYed with Titanolepas 947 



Through the industry of the late Mr. F. Mockler, I have been 

 enabled to examine a large series of Cirripede remains Avhich he 

 obtained from the Cenoraanian Chalk Marl in the neighbourhood 

 of Cambridge. By far the greater number can be referred to two 

 species, which add materially to our knowledge of the phylogeny 

 of the pedunculate Cirripedes. 



One, Zeugmatolepas moclderi, gen. et sp. n., is represented by 

 two nearly complete capitula and portions of nine others, as well 

 as a large number of isolated valves. It is interesting from the 

 fact that, while it agrees with- the species of PoUicij:)es in the 

 number of valves of the cajaitulum, it differs not onl}' in the 

 more specialized form of scutum, but also in the size and position 

 of the upper latera, which are nearly as large as the scuta, and 

 have become elevated to occupy the whole of the space between 

 the scuta and terga. This form ceitainly serves more than any 

 other to connect the genus FoUicipes to ScalpeUum, and, together 

 with S. (?) cretm Steenstrup sp., from the Upper Senonian of 

 Denmark, is now included in the new genus Zeugmatolepas. 



The second species, ScalpeUum tuberculatttm Darwin, is repre- 

 sented by a large number of separated valves, including several 

 not previously known. These enable us not only to reconsti-uct 

 the capitulum, but also to show that the species must be referred 

 to the genus Calantica Gray. Representatives of that genus 

 are now found living, and the geologically oldest species of its 

 subgenus Scillcelepas, to which Scalpelhim tuberculatum comes 

 nearest, occurs in the Miocene of Italy. The recent and 

 Tertiary species have the umbones of all the valves apical, so 

 that it is surprising to find in the Cretaceous I'epresentative, 



* Communicated by Dr. W. T. Calman, F.Z.S. 

 t For explanation of the Plates see p. 948. 



