304 Davidson — Earliest British Brackiopoda, 



oldest animal form on record, it becomes most interesting to seek 

 out the exact period at which the next animal, or series of animals, 

 made their appearance in the waters of our globe. It will, there- 

 fore be my object in this brief communication to investigate the 

 earliest Brachiopoda that have been discovered up to the present 

 time in the * Primordial rocks ' of Great Britain. I had hoped, it 

 is true, that my friends, Messrs. J. W. Salter, H. Hicks, T. Belt, 

 E. Williamson, J. Plant, and same others, who have devoted so much 

 time to the study and elaboration of the Cambrian and Lowest 

 Silurian rocks of North and South Wales, and who, during their 

 lengthened investigations, had assembled so many specimens, would 

 have likewise completely worked out the new species of Brachioj^oda 

 they had discovered ; but as a desire was expressed that such should 

 be done by myself, I will now endeavour to carry out their wishes, 

 although the task involves a certain amount of difficulty, from the 

 circumstance that several of the species are very minute and occur 

 only under the condition of internal casts and more or less perfectly 

 preserved external impressions. 



It would not be possible in the short space into which the present 

 communication must be compressed, to even refer to the many very 

 important geological or stratigraphical labours that have been pub- 

 lished upon these primordial rocks and fossils by Sir E. I. Mur- 

 chison, the Eev. A. Sedgwick, Prof. Eamsay, Messrs. Salter, Hicks, 

 Belt, and several others ; ^ but with the kind assistance of the 

 last two named gentlemen, an attempt has been made to tabulate the 

 vertical range of strata, as well as of each of the species of Brachio- 

 poda, so far as such was practicable, and I will consequently, with- 

 out further preamble, proceed to describe the various forms that have 

 come under my notice : — 



Grenus Lingulella, Salter, 1861. 



At page B5 of my Silurian Monograph will be found a full descrip- 

 tion of this genus, so far as we are at present acquainted with its 

 internal characters. I was, therefore, somewhat surprised while 

 reading in the twenty-third volume of the Quarterly Journal of the 

 Geological Society (p. 341), '' that I had shown a bad example by 

 merging Lingulella into Lingula (though the one has a pedicle 

 gi'oove and the other has not)." If I, therefore, revert to this, no 

 doubt, unintentional mistaken statement, it is simply in order to re- 

 iterate that I adopt Lingulella as a section in the great family 

 Lingulidce, and, as far as my observations extend, that all the speci- 

 mens of the genus hitherto discovered in the ancient Palaeozoic 

 deposits of our British Islands would be referable to the three 

 following species : — 



1. Lingulella Davisii, M'Coy. PI. XV. Fig. 13-15. 



This is the largest, but not the most ancient species of the genus 



^ My thanks are also due to Messrs. J. Plant, R. A. Eskrigge, G. H. Morton, D. 

 Homfruy, and J. C. Barlow for the communication of their specimens ; but parti- 

 cularly to Messrs. II. Hicks and T. Belt, who have presented me with a fine and 

 extensive series of specimens collected by them in North and South Wales. 



