118 T. H. Withers — Some Palaeozoic Fossils 



The recent sessile Cirripedes are included in the families Balanidae 

 and Verrucidae, the latter family consisting of the asymmetrical 

 Cirripedes forming the single genus Verruca. Verruca extends back 

 in time to the Cretaceous (Upper Senonian), and I have recently 

 maintained (Proc. Zool. Soc, December, 1914, pp. 950 et sqq.) that 

 it was derived from the more primitive form Proverruca, occurring 

 also in the Cretaceous (Lower Senonian). In its structure Proverruca 

 shows quite conclusively that it must have been derived from a 

 symmetrical pedunculate Cirripede such as Calantica (Scillcelepas), so 

 that the Yerrucidae at any rate were derived from a stalked form. 



The Balanidae consists of the sub-families Balaninae and Chthama- 

 linae. We have some evidence to support the supposition that the 

 Chthamalinae (Catophragmus) have arisen from some such form as the 

 Cretaceous (Upper Senonian) sessile Cirripede Brachylepas, which in 

 all probability was an offshoot from the stalked Cirripedes forming 

 the genus Pgcnolepas 1 (Cretaceous, Albian, to Miocene, Helvetian). 

 On the other hand we cannot derive the Balaninae from that source or 

 from any known form in either the Cretaceous or Jurassic rocks. 



Since, however, both the Verrucidae and the Chthamalinae can be 

 traced back to the stalked forms existing in the Cretaceous, it seems 

 very unlikely that the remaining 'sessile' group among the recent 

 Cirripedes, the Balaninae, can have any close relationship with the 

 ' sessile ' Palaeozoic forms. It is much more probable that the 

 ancestors of the Balaninae are to be sought for in the Upper Cretaceous 

 or early Tertiary rocks. Further, while among recent Cirripedes the 

 sessile condition is undoubtedly due to a secondary modification of 

 the pedunculate type, it must be kept in mind as a possibility that 

 this may not have been the case among the more primitive forms of 

 the Palaeozoic rocks. We can as yet form only a vague idea of the 

 ancestral Cirripede, but there is no need to assume that it possessed 

 a peduncle. 



Cirripodites, Gr. F. Matthew, and Sthnotheca, J. W. Salter. 

 In a paper on the " Faunas of the Paradoxides Beds in Eastern 

 North America, No. 1 " (Trans. N.Y. Acad. Sci., vol. xv, pp. 200-7, 

 1896), Dr. Gr. F. Matthew has described from the Cambrian 

 certain scattered plates which he ascribes to a new genus Cirripodites, 

 and to the genus Stenotheca, Salter. 2 The latter genus was found by 

 Salter to include a minute, cap-shaped shell, which he considered to 

 be a Pteropod. but which is now classed among the Gastropods. 

 Even if the forms described by Matthew are not Pteropods or 

 Gastropods, I can see no valid reason for their reference to the 

 Cirripedia, and the comparative thickness of certain of the plates is 

 certainly not in favour of this reference. With regard to the plates 

 included in Cirripoditex, I fail to see any characters in common with 

 any Cirripede, and I find no reason for dissenting from Matthew's 

 own opinion that ".The reference of these plates to Cirripedes is 

 largely a matter of conjecture". 



1 See T. H. Withers, " Some Cretaceous and Tertiary Cirripedes referred to 

 Pollicipes " : Ann. Mag. Nat. Hist., August, 1914, pp. 199 et sqq. 



2 J. W. Salter in H. Hicks, Quart. Journ. Geol. Soc, vol. xxviii, p. 180, 

 1872 ; J. W. Salter, Cat. Camb. Sil. Foss. Mus. Camb., p. 8, 1873. 



