71 



We cannot help exprefTing fome doubts with refpefl to UMBiLtdAtu*. 

 iheMyt/lus umhilicatus hemg a dilHnfl fpecies ; Mr. Pen- p- 1<>4. 

 NANT was the firft who publicly noticed it, and it was af- 

 terwards defcribed by other EngliQi authors upon his 

 authority. There are however fome circumftances from 

 which it is reafonable to con)e6lure that it is only a lufus of 

 M. Modiolus. It muft be confelled we have long been in- 

 duced to this opinion, but did not venture to pronounce it, 

 till we found other conchologifls inclined to accord with us, 

 Mr. Laske¥ informs us he has a fpecimen of Mytilus de~ 

 mejfus, and another of M. edulis with fimilar depredions ; 

 and of the laft fpecies one occurs in our own cabinet ; fo 

 that it is but a reafonable conclufion tliat Modiolus may ac- 

 cidentally afllime the form in which we find umbilicatiis. 



That there is no other diftin(5lion between thefe fliells 

 than the depreffion near the beak will not be difpufed, and 

 the fcarcity of the latter favours the fuppofition. It has not 

 been defcribed by any foreign author, nor has it we believe 

 occurred above two or three times to Englifh collectors. 

 Under all thefe circumfiances we cannot help concurring 

 with Mr. Laskey and Ibme other conchologifls that the 

 three formerly defcribed fpecies of Mytilus, the curtus, mo» 

 diolus, and umbilicatus of the BniiJJj Zoology, are one and the 

 fame. 



The great variety of fliape obferved in Mytilus edulis 

 muft alfo favour an opinion that the incurvatus origi- 

 nally defcribed by Mr. Pennant, is no other than a dif- 



torted 



