156 CLASS I. TROPIOPODA. ORDER II. UNIMUSCULOSA. 



LIMA, Bruguiere. 



Testa longitudinalis, subsequivalvis, insequilateralis, auriculata, latere uno 

 subhians. Umbones divaricati, parietibus internis extrorsum decli- 

 vibus. Cardo edentulus, sed interdum ad utrumque latus indistinct^ 

 crenulatus. Ligamentum parti in externum, in medio area? obliqua?, 

 in fossula trigona insertum. Impressio musculi sublateralis. 



The Lima?, together with the Pectinea, were placed originally in the 

 genus Ostrea on account of their shells being destitute of teeth ; and in 

 this situation they remained until Bruguiere, the great reformer of the 

 Linnasan system, proposed the alteration that has been since adopted. 

 Poli asserts that the Lima? are intimately allied to the Aviculce, both 

 having a byssus, and actually proposes to unite them in one and the 

 same genus, under the title of Glaucoderme. Lamarck, indeed, being 

 persuaded that they were provided with a byssus, included the genus 

 under consideration (probably on the authority of Poli) with Avicula in 

 his family of Les Byssiferes ; but subsequently, on the formation of his 

 family of Les Pectinides, he arranged the genus Lima in the situation 

 which is here assigned to it, and in which he has been followed by De 

 Blainville, Gray, and most of the leading conchologists. Now, however, 

 the propriety of arranging the Lima? in the family of the Pectinacea has 

 become rather questionable ; Deshayes asserts that they differ materially 

 in their organization from the Pectines, to which they have been latterly 

 considered as most intimately allied, and that they ought indeed to con- 

 stitute a new and particular family. This opinion appears to have been 

 advanced on the anatomical observations of Quoy, — authority, which it 

 is as painful to doubt, as it is difficult to dispute. Much as we respect 

 the labours of this skilful malacologist, we must content ourselves by 

 merely putting this opinion upon record : the shell of Lima does not 

 certainly approximate to that of Pedum ; there is no basal notch for the 



