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134 T Couthouy's Monograph on 
to him by M. de Gerville, as A. myális, being really A. 
iaptboiiéea ; and, that recognising it as the latter, and 
authority of M. de Gerville for its 
, he determined the two species to be 
This is farther confirmed by his observation, p. 660, 
where, speaking of Periploma, he says, * nous l'avons 
caractérisé d’après I Anatina myàlis, connue sur nos 
cotes, et dont nous devons la connoissance, ainsi que 
celle de son animal à M. de Gerville. L/osselet singu- 
lier qui en fait le caractére principal, est. contenu dans 
une sorte de gaine transverse, qui entoure un repli de 
manteau. C'est cette.espéce à dent mobile, dont il est 
parlé à la fin des observations sur le genre ANATINE.” 
Now, on turning to the passage referred to (p. 564), we 
read — * M. Deshayes nous a fait faire l'observation 
que l'anatine trapézóidale a une dent mobile sur la valve 
droite, et se logeant dans l'angle formé par le euilleron."' 
M. Deshayes moreover, in his continuation of Lamarck, 
published nearly ten years after the Man. de Malac., 
speaks of P. trapezoides as the only species yet known 
to him; whereas, if M. de Blainville’s had not been that 
shell, there would of course be another. It is necessary 
therefore, to restore A. myalis as a Thracia, it having been 
suppressed by M. de Blainville, p. 660 of his Manual, 
on false data. It may, however, reasonably be doubted 
whether there is any utility i in his division of that genus 
into A, those with a nymphal callosity on one valve 
only, of which he gives T. corbuloides as an instance, 
. No such distinction is admitted by M. Des- 
hayes, and. in several undoubted specimens of T. 
‘and B, those having a callus on both valves, as in T- 
pubéscens 
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