126 BRITISH CARBONIFEROUS BRACHIOPODA. 



others, the intervening striae nearly equal the principal ones in size, and the shell appears 

 more closely and coarsely striated sub- alternately : but both extremes may be seen on the 

 one specimen, and the differences are clearly the result of the loss of one or more layers of 

 shell." I have also had the advantage of being able to examine typical examples of Pro- 

 fessor Hall's 0. Keokuk and 0. robusta, which were kindly presented to me by Mr. 

 Worthen, and am thus enabled to affirm that these American shells cannot be specifically 

 distinguished from British varieties of S. crenistria. 



For a long time I felt puzzled how to deal with a certain curious fragmentary ventral 

 valve, figured by Mr. J. de C. Sowerby, in the ' Mineral Conchology,' under the designation 

 of Zepfcena anomala (tab. 615, fig. 1, b), and which I have also represented in PI. XXX, fig. 

 15. This shell was subsequently referred by Messrs. Salter and Morris to the genus 

 Strophalosia, and united with it under the same denomination was Productus striatum ; 

 but here a double error has been committed, for the shell in question is neither a 

 Strop/ialosia, nor does it belong to Productus striatus, which is an entirely different 

 species, although so confounded likewise by Mr. J. de C. Sowerby. Having received 

 from Mr. Burrow some curiously shaped examples of Strept. crenistria, (PI. XXX, fig. 14), 

 I at once perceived that Zept. anomala was no other than a malformation of Phillips's S. 

 senilis, and consequently a Strep tor Jti/nchus, while the Mytilus striatus of Fischer belongs 

 to the genus Productus. 0. quadrata was created for a very small imperfect ventral 

 valve of a Streptorltynchus, which looks very like a young S. crenistria ; and the shell, such 

 as it is, belongs to Sir R. Griffith, and is said to have been found in calp at Ballintrillick, 

 Bundoran, Ireland. Its striation is exactly similar to that of crenistria, and to which it 

 is referred at least provisionally, the material being too imperfect to admit of its 

 being regarded as a well made-out species. Such are some of the undoubted synonyms 

 of Phillips's species, and to which I would have added others, but for the reasons already 

 given. 



S. crenistria appears to have had a very extended vertical range, and is recurrent from 

 the Devonian if not Silurian period ? In the Carboniferous rocks, it is found in all the 

 stages, from the lowest beds (such as the Lower Carboniferous Red and Yellow Sandstone of 

 Kildress) up to the highest beds above the Mountain or Carboniferous Limestone. It is 

 also a far-spread species, having been found in various parts of Europe, America, Asia, and 

 Australia, everywhere assuming the same shape and variety. 



In England, it occurs at Bolland, Kendal, Settle, the Isle of Man, &c. ; in Scotland, 

 at Bowertrapping, three miles south of Dairy, and in many localities in Lanarkshire, 

 Renfrewshire, Dumbartonshire, Ayrshire, &c. It was figured by David Ure, in his ' History 

 of Rutherglen and Kilbride (pi. xiv, fig. 19), as far back as 1793. In Ireland, it occurs 

 in many localities ; among which may be mentioned Hook, Bundoran, Bally duff, 

 Millecent, &c. 



In Belgium, it is found at Vise and Tournay, &c. In America at Keokuk, Iowa • 



