202 SUPPLEMENT TO THE BRITISH 



' Prodrome/ A. d'Orbigny quotes this species from the Great Oolite, or Etage Bathonien, of 

 different places in France, and at p. 343 of the same work he alludes to it from the 

 Kelloway Rock, or his Etage Callovien ; but M. E. Deslongchamps informs us, at p. 54 of 

 the second volume of the ' Bulletin of the Linnsean Soc. of Normandy,' that all these 

 identifications are incorrect, and that he has not found it higher up than the Inferior 

 Oolite. 



192. Rhynchonella pygivlea, Morris. Dav., Ool. Mon., p. 57, PI. XIII, figs. 16, 



16 a, b, c. 



Since publishing my figures and description of this species, I have found that it is 

 referable to the genus Bhynchonella, and not to that of Terebratula. Bh. pygmeea was 

 found by Mr. C. Moore in the Leptaena bed of the Upper Lias near Uminster, 

 associated with Ter. globulina. In 1861 it was also quoted by the Rev. E. Smithe from 

 the zone of Am. communis of the Upper Lias of Churchdown, in Gloucestershire. It is 

 not, however, an abundant fossil, or rather, being confined to a narrow area, is not so 

 easily collected. In an admirable paper on the Ammonites communis zone published by 

 the Rev. P. Smithein the ' Proceedings of the Cotteswold Naturalists' Club,' August, 1861, 

 he states " Bh. pygmaa is the brachiopod most conspicuously present, followed by 

 T. globulina and Lejjtana. 



" i 



1 The Rev. F. Smithe further observes, " Reference may here be made to the dwarfed size of the 

 organisms of the zone, as though starvelings of a larger race, that came from a distance and struggled for 

 existence. Whether the waters of our Liassic estuary were deficient in a normal percentage of salt is a view 

 not unworthy our consideration. Such a cause would adequately suffice to degenerate the Mollusca 

 inhabiting them. Russian naturalists tell us that while Oysters, for instance, are found in the Mediterra- 

 nean, the Atlantic, the North Sea, and the northern part of the Cattegat, they do not occur in the Baltic 

 Sea, and refuse to be naturalised there. To accord with this, the Oyster cited in my list is almost a 

 solitary example, not an inch in diameter. The waters of the Mediterranean contain 3"7 per cent, of salt ; 

 those of the Atlantic 3 to 36 per cent. ; the north of the Cattegat T8 to 2 per cent. ; while the saltest part 

 of the Baltic yields only T7 per cent, of salt. In Prof. Forbes's 'Travels in Lycia,' 1847, it is mentioned 

 that a gradual change in fossil marine species of Mollusca was observed by the writer in some coast 

 sections of the Island of Cos. The deviations in form evidently arise from the influx of fresh water. 

 Every algologist must have noticed the stunted dimensions of such marine Algae as contrive to live in 

 brackish waters, or in salt water commixed with a large proportion of fresh. A specimen of a given 

 plant gathered in pure salt water and placed by the side of the same plant taken from brackish streams 

 would only be recognised as identical by an exceptional botanist conversant with the method of gradation. 

 The waters of the ocean, then, when reduced in their due quantity of saline matter, have undeniably the 

 power of dwarfing the marine forms of animal and vegetable life, and seem to have done so here, 

 transmittng us a puny, diminutive fauna." 



