25S H. Woodward — New Fossil Crustacea. 



succeeded by Elephas and Hippopotamus, and by other Ehinoce- 

 roses, with which perhaps the Mastodon still lingered on ; whilst 

 these again in turn gave way to yet other species of Elephant and 

 large mammalia, and to these succeeded the historic fauna. These 

 changes in the terrestrial fauna are thus briefly alluded to, in order 

 to draw the line between them and the changes of the marine fauna 

 as indicated by the mollusca, etc. It is a fundamental law of distri- 

 bution that contiguous marine and terrestrial faunas are rarely 

 similarly affected by the same cause. Hence, whilst the sea may 

 have undergone such changes as to convert its fauna from one of 

 ''Miocene" facies to one of sub-arctic facies, the same great 

 mammals — all or only some — may have continued to hold the land. 



In conclusion, I have to record a new Cetacean from the Suffolk 

 Bone-bed, indicated by a flattened foliaceous tooth with a dentate 

 margin, probably belonging to the genus Squalodon. 1 have also 

 further evidence of Hycena antiqua. 



III. — CONTKIBUTIONS TO BrITISH FoSSIL OrUSTACEA. 



By Henry Woodward, F.G.S., F.Z.S. 



[PLATE XIV.] 



j^ pYBGOMA CBETACEA, H. Woodw.— In my first Eeport on 

 Fossil Crustacea (Brit. Assoc, for the Advancement of 

 Science, 1865, Reports, p. 321), I called attention to the occurrence, 

 in the Upper Chalk of Norwich, of a sessile Cirripede belonging to 

 the genus Pyrgoma. This unique example — for which I proposed 

 the name of Pyrgoma cretacea — was discovered by Mr. T. G. Bayfield, 

 of Norwich, who forwarded the specimen to the British Museum 

 where I had the good fortune to detect its character. As no other 

 specimen of this new species has been met with, I have thought it 

 advisable (although only an imperfect example) to place.it on record 

 in the hope that better ones may be found. It is represented in the 

 accompan3dng Plate XIV., Figs. 1 and 2, of the natural size. 



The genus Pyrgoma was proposed by Leach (Joum. de Physique, 

 tome 85, 1817) for a minute form of Balanus obtained living, on the 

 south coast of England and Ireland, Sicily, Madeira, St. Jago, and 

 the Cape de Verde Islands ; generally found attached to the edge of 

 the cup of a coral belonging to the genus Caryopliyllia. The shell 

 is formed of a single piece ; the basis, cup-formed or sub-cylindrical; 

 the scutal and tergal valves are articulated together.^ 



The only fossil species hitherto recorded belonging to the genus 

 Pyrgoma, are the Pyrgoma undata, of Michelotti,^ from the Miocene 

 Tertiary strata of northern Italy ; and the Pyrgoma anglicum (Sowerby), 

 from the Coralline Crag of Suffolk, which Dr. Darwin considers to 

 be identical with the recent British species.^ 



The single fossil example we possess consists of about two-thirds 



1 Darwin Foss. Cirripedia, Pal. Soc. Men., 1854, pp. 35, 36. 

 ' Bulletin Soc. Geol., torn. ix. p. 141. 

 3 Darwin Foss. Cirripedia, p. 36. 



