Contributions to the anatomy of anthropoid apes / by Frank E. Beddard.
- Frank Evers Beddard
- Date:
- 1893
Licence: Public Domain Mark
Credit: Contributions to the anatomy of anthropoid apes / by Frank E. Beddard. Source: Wellcome Collection.
112/246 page 264
![VIL Affinities of the Fauna. The preceding list shows that the Bryozoa included in the present paper belong to three fairly distinct faunas, but a comparison of the three shows that they possess certain features in common. In the first place, each of the three faunas is numerically small, both in species and individuals, in comparison with the wealth of forms that inhabited the contemporary seas of the Mediterranean basin. The stunted and dwarfed aspect of the three faunas is apparently due mainly to climatic conditions. As has been pointed out in a recent revision of our Eocene Echinoids l, the British seas of that period were confined to the south by a land barrier which stretched across France and Northern Germany. Hence to the south of this area the Bryozoa flourished under favourable conditions in a tropical and subtropical ocean, while on the other side the seas were open to the chilling influences of the northern ocean. The land barrier was breached in Middle Eocene times, but the conditions were not seriously modified till later: then, with the gradual change to the brackish and freshwater deposits of the Oligocene, the marine Bryozoa cease to be represented in the British Palaeogene. The Echinoids of the period belong to the same genera as their contemporaries in the Mediterranean basin, but their generally dwarfed aspect and rareness indicate that they lived under unfavourable conditions. The Bryozoa present exactly the same parallel. An effort has been made to explain the paucity of Bryozoa in English deposits of this period as due simply to unfavourable lithological conditions of life and preserva- tion. The prevalence of clay and sharp sand is quoted as unfavourable to the growth of Bryozoa. But this is hardly sufficient. The shelly sands of the Bracklesham, on the contrary, would seem to indicate the conditions that would be most favourable to the existence and preservation of Bryozoa. That the clay shores of the London Clay and Barton are wholly responsible for the rarity of the Bryozoa is not likely to be accepted by any one who has dredged on the great mud-flats off the Essex coasts, where it is often difficult to procure a shell not encrusted by them. In other districts, such as the Paris basin, Belgium, and North Germany, which were also to the north of this land barrier, and where the lithological characters of the sea-floors were quite different from those of England, the Bryozoa are equally rare and stunted. Hence, it is to geographical questions rather than to the lithological conditions of the sea-floor that we must attribute the marked characters of our Palaeogene Bryozoan fauna. The singular diversity of the fauna is another feature which supports the view that it is to be regarded as a remnant or an offshoot from one that was much greater and richer. Mr. Waters [Nos. 12 & 13], in his revision of the Oligocene Bryozoa of North Italy, admits 88 species, representing 35 genera. But the British fauna contains only Gregory, Proc. Geol. Assoc, xii. 1891, pp. 51, 52.](https://iiif.wellcomecollection.org/image/b28141386_0112.jp2/full/800%2C/0/default.jpg)
