160 



BRITISH SILURIAN BRACHIOPODA. 



Obs. The history of this variable and interesting species may prove valuable as 

 exemplifying the difficulties at times experienced by naturalists in arriving at the 

 correct identification of some of our most characteristic species. In 1839 J. de C. 

 Sowerby first noticed the shell as a distorted cast of a large Spirifer or Orthis, nearly three 

 inches in length, to which he applied the name of Spirifer liratus, giving as its locality 

 the " Caradoc sandstone " and " Llandeilo flags " of Marloes Bay, Pembrokeshire. Mr. 

 Sowerby's specimen was very imperfect, merely a portion of the cast of a distorted valve ; 

 and the position was subsequently corrected by Mr. Salter in ' Siluria.' In 1846 Prof. 

 M'Coy gave a short but correct description and reduced figure of a valve of the same 

 species (see PI. XX, fig. 8) under the designation of Spirifer ovatus, remarking that it is 

 the largest Silurian Spirifer with which he is acquainted. Prior, however, to this date, 

 I should have observed that the same species had (in 1842) been described and figured 

 by Hisinger, under the designation of Cardium muUisulcatum. In 1848 M. de Verneuil 

 mentions it as a Spirifer, retaining Hisinger's specific name ; and in the same year 

 Messrs. Phillips and Salter refer to this shell under the designation of Orthis liratus. 

 In 1852, while I was preparing the "General Introduction" to the present work, 

 Mr. Salter called my attention to this shell, as well as to Pent, lens, suggesting that they 

 should be grouped as a section of Pentamerus, presenting well-marked internal characters? 

 at once distinguishing them from true Pentameri, such as P. Kniglitii, P. galeatus, 

 P. linguifer, &c. A description of these internal characters will be found in p. 54, 

 pi. vii, fig. 118, of the above-mentioned "Introduction," as well as in p. 227 of my late 

 friend Dr. S. P.Woodward's excellent 'Manual of the Mollusca,' published in 1854. 

 At p. 229 of the second edition of ' Siluria,' (1859) Mr. Salter, to whom Sir Roderick 

 Murchison had confided the revision and notes of the fossil data in his work, observes, 

 M-hile speaking of the Brachiopoda of the Llandovery rocks, that "The Pentameri 

 are, however, the characteristic fossils, which impart to this 'zone its peculiar and 

 distinct facies. No less than five species, whether smooth or only shghtly ribbed, 

 occur, and of these P. oblongus is the best known and the most widely spread. 

 This typical shell is easily distinguished from the other species, P lens and P. liratus, 

 by the great length of the mesial septum, which in these latter is quite a short 

 appendage to the V-shaped chamber. The two longitudinal plates, also, which divide 

 the upper valve, are peculiar to this species ; whilst in P. lens they are very short, and in 

 P. liratus are reduced to a pair of processes which pass inwards, but do not show upon 

 the surface of the cast." 



In 1860 Dr. Lindstrom describes the same shell as Cijrtina^ miiltisulcata ; but soon 

 afterwards, recognising his mistake, he identified his Gothland shell w4th Pentamerus 

 liratus. Lastly, Mr. Billings, availing himself of the difierential characters pointed out 

 by Salter, proposed for such shells as P. liratus, P. lens^ and some other Canadian and 

 American species, the generic designation of Stricklandia, and which he subsequently 

 altered to Slricklandinia. This I will retain as a section of the large genus 



