ox A REMARKABLE NEW CIRRirEDE. 945 PAPERS. •50. A remarkable new C-irripede from the Chalk of Surrey and Hertfordshire. By Thomas H. Withers, F.G.S.* [Received May 27, 1914 : Read October 27, 1914.] (Plate I.t and Text-figure 1.) Index. Page Iiiti'oduction 945 Structure of Provemica 950 Evolution of the Verrucidaj 951 Distribution (Geological), Cretaceous of England, Pru-verruca-, Scalpellum (sensu lata) 946, 952 Proverruca vi)i<:ulum, gen. et sj). n 940 Provemica compared with Verruca and Calaiitica (Scillmlepas) 950 Seal pellum vimineum, sp. n 952 Among some Cirripede remains recently collected from the Chalk of Surrey are a number of isolated valves, which, together with a remnrkably complete specimen of the same species from the Chalk of Watford, Hertfordshire, throw much light on the evolution of the sessile Cirripedes of the family Verrucidaa. Tiiey constitute, in fact, the '"missing link" between the pedunculate Cirripedes of the family Pollicipedidas and the sessile asym-metrical Cirripedes of the family Verrucida?. The valves fi'om Surrey were obtained by me from a mass of unusually soft Chalk found by Mr. C. P, Chatwin in the Slines Oak Pit, Worms Heath, near Woldingham, and to judge from the .single example of Micra^ter prcrxursor collected fi'om the same horizon, the chalk appears to be in the upper part of the zone of Micraster cor-testudinarium. This is the zone to whish it has been assigned by Mr. G. W. Young j. Much difficulty w.is experienced in studying these valves, for although they were all somewhat similar in extei-nal ornament, the scuta and tei'ga differed so much in structure that it was apparent that more than one species was I'epresented. What was evident, however, was that certain of the scuta and terga, appar-ently of the same sj^ecies, were extremely convex ti'ansversely and formed a semicircle when placed in position. This fact suggested to me the possibility of their belonging to a new form of sessile Cirripede, since if the capitulum were completed it would approach iTioi'e closely to radial symmetry than is the case in an ordinary * Communicated by Dr. W. T. Calma>% F.Z.S. + For explanation of the Plate see p. 953. X 1905. "The Chalk Area of North-east Surrey," Proc. Geol. Assoc. London, vol. xix. p.208{pit 127a). Proc. Zool. Soc— 1914, No. LXIY. 64
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