204 Mr. T. H. Withers on some 



a subgenus of Calantica, differs iu the form of the scutum 

 from the other members of the genus. It existed in the 

 Cretaceous (Cenomanian and Turonian), and is considered 

 to be an early specialized form, which branched ofl' from the 

 main Scillalepas line and may eventually have given rise to 

 the genus Oxynaspis. 



Although we can gain some idea of the phylogenetic 

 position of the Cirripedes discussed in this paper, even with 

 the small number of forms and the meagre evidence at our 

 disposal, it is obvious that a knowledge of their Jurassic 

 ancestors would help materially. Unfortunately, the Jurassic 

 species are known in the main only by a few disconnected 

 valves, which give very little idea of the form of the capi- 

 tul,um ; and until our knowledge of these forms is con- 

 siderably extended^ our conception of the evolution of the 

 group^ as a whole, can make little progress. 



In conclusion, I wish to express my indebtedness to the 

 following gentlemen, who have kindly helped me either by 

 the loan or gift of specimens, or in other ways : — Prof. G. 

 de Alessandri, Dr. F. A. Bather, Dr. H. P. Blackmore, 

 Mr. R. M. Brydone, Dr. W. T. Caiman, Mr. C. P. Chatwin, 

 j\Ir. F. Leney, Dr. K. Briinnich Nielsen, Prof. C. F. Parona, 

 Dr. J. P. J. Ravn, and Count Luigi di Rovasenda. 



EXPLANATION OF THE PLATES. 

 Plate VII. 



Pycnolepas paronai, de Alessandri, sp. 



Miocene (Helvetian) : La Grangia, Colli di Torino, Italy. 



Fig. 1. Rostrum. 



Ftg. 2. Scutum. Imperfect left valve. 



Fig. 3. Tergum. With base broken off. 



Fig. 4. Carina. X 2 diam. Coll. R. Museo Torino. Origl. figd. G. de 



Alessandri, Palaeontogr. Ital. 1906, vol. xii. p. 248, pi. xiii. 



fig. 8. 



All figures, except fig. 4, nat. size. 



Pycnolepas hriinnichi, Withers. 

 Danian, Bryozoa Limestone : Faxe, Denmark. 



Fig. 5. Rostrum. 



Fig. 6. Scutum. Right valve, with rather narrow apico-basal ridge. 



Fig. 7. Upper latus. Apex broken oti". 



Fig. 8. Tergum. Right valve. 



Fig. 9. Carina. 



All figures X 4 diam. 



