17G Mr. T. H. Withers o« some 



1886. roUicijyes fnllax, Darwin ; J. Kafka, Sitz.-Ber. k. B;ihm. Gesell. 

 Wi!^s. Prao- (1885), p. 571, pi. iii. figs. 2, 3 (partim). 



1887. Pollicipes falla.v, Darwin ; A. J. Fritscli and J.Kafka, Crust. 

 Bohmiscbeii Kreidef. p. 10, tig. 17 (partim). 



1888. Mitella fallax, Darwin, sp. ; A. Perou, Bull. Soc. Sci. Yonne, 

 vol. xli. (1887) p. 267, pi- iii. figs. 5-9. 



1893. PoUicipes fallax, Darwin ; A. Fritsch, Arch, naturw. Landesd. 



Bohmen, Prague, vol. ix. p. 108, fig. 143. 

 1902. Follicipes fallax, yiarvi-in; A. WoUeman, Abb. k. preuss. geol. 



Landesanst. N. F. Ileft 37, p. 115. 

 1906. Brachi/lepas fallax, Diivwin, sp. ; H. Woodward, Geol. Mag. 



dec. V. vol. iii. p. 340, figs. 5-18. 21-22, 24 (non figs. 19, 20, 23). 

 1912. Polh'cipes fallax, Darwin ; T. H. Withers, " Cirripedes in the 



Norwich Museum from the Norfolk Chalk, studied by Darwin," 



Trans. Norfolk and Norwich Nat. Soc. vol. ix. p. 309. 



Diagnosis. Capitular valves ridged transversely, but not 

 longitudinally, or at least very weakly so. Scuta elongately 

 triangular, with a ridge with sloping sides curving from the 

 apex to the basi-lateral angle. Terga with a similar ridge 

 curving from the apex to the basal angle. 



Distribution. Upper Senoniau, B. mucronata-zoue : Nor- 

 wich and Trimingham, Norfolk ; Clarendon, near Salisbury, 

 Wilts ; I. of Rugen ; Liineburg, Hanover. A. quadratiis- 

 zone : East Harnham, near Salisbury, Wilts ; Reims, France. 

 M. coranginnum-zowe: Quidhampton, near Salisbury, Wilts. 

 Upper Senonian : Gehrden, Hanover ; ? Flauen, near Dres- 

 den ; Ciply and Heure-le-Romain, Belgium ; Nagorzani, 

 Galicia ; near Lliota Ureticka, and Chotzen, Bohemia ; 

 Balsberg and Kopinge, Scania. 



Type. Of this species Darwin had only scuta and terga; 

 his figured types*, the scutum and tergum from the Chalk 

 of Norwich, are in the Norwich Museum, registered respec- 

 tively 2153 (iectoholotype), 2153 c. 



Material. Further valves, coming from different horizons, 

 have been made known by later authors, but we are indebted 

 more particularly to Bosquet (1857) and H. Woodward 

 (1906) for our knowledge of the species, especially since the 

 valves figured by them are from one horizon. 



So far it can be proved that P. fallax had a rostrum, 

 paired scuta, paired upper latera, paired terga, and a carina, 

 and all these valves are of the same general type as in 

 BrachijlepaSj except that the carina and rostrum are longer 

 and narrower, just as in the other species included in the 

 new genus Pycnohpas; the arrangement of the valves is 



* See T. II. Withers, 1912, Norfolk and Norwich Nat. Soc. vol. ix. 

 p. 309. 



