436 Mr. T. Davidson on the Brachiopoda. 



muscles des Ter^bratules, et en partieulier de la Terebratula 

 australis** (Academie des Sciences, Paris, 11 July 1853), but 

 printed some short time after our Introduction had gone through 

 the press. My object not being to enter upon a detailed account 

 of the muscles, which have been fully described elsewhere, I 

 must refer the reader to the French author's paper* ; contenting 

 myself with reproducing in this place a translation of that portion 

 only which relates to the subject under discussion. After refer- 

 ring to the different opinions advanced by authors as to the 

 mode in which Terebratulce open their shell. Dr. Gratiolet states 

 that " all these hypotheses are more or less ingenious, but do 

 not satisfy a severe investigator. Prof. Quenstedt alone seems 

 to me to have arrived at the true explanation (Wiegmann's 

 Archiv, vol. ii. p. 220, 1835). This able anatomist, founding his 

 views on very precise reasons derived from the mode of articu- 

 lation of the valves, was the first to point out two orders of 

 muscles, of which the one closed, while the other opened the valves. 

 Unfortunately Prof. Quenstedt's paper is both short and without 

 plates'' (this last statement is not strictly correct, since we 

 find three diagrammatic figures), " so that the opinion of this 

 clever author did not make way, and is not even alluded to 

 in MM.^Siebold and Stannius's Manual, which is otherwise so 

 complete. This unjust forgetfulness has appeared to me worthy 

 of being noticed ; besides which, among the descriptions which 

 have been given of the muscles of the Terebratulce, not one is to 

 my mind intelligible, and I have therefore deemed it useful to 

 revert again to a subject so interesting." After having read the 

 above, I lost no time in procuring a copy of the paper so highly 

 spoken of by the French savant, and of which I now offer the 

 entire translation. 



On the mode in which Brachiopoda open and close their Shell. 

 By Prof. Quenstedt f- PI- X. figs. 6, 7, 8. 



" Prof. Owen's anatomy of several Terebratula has excited the 

 greatest interest J. In general we may place the utmost con- 

 fidence in the researches of that author, on account of his beau- 

 tiful works and investigations on other subjects. But when, 



* In the explanation of the Plate I have reproduced the names given by 

 M. Gratiolet to the muscles, also those by Prof. Owen, and those used by 

 myself. 



t Ueber das OefFnen und Schliessen der Brachiopoden. Wiegmann's 

 Archiv, vol. ii. pp. 220-222. pi. 4. f. 4, 5, 6, 1835. 



:|: Prof. Quenstedt means Prof. Owen's first paper published in the 

 Transactions of the Zoological Society. 4to. Vol. i. 1835. 



