42 " LUCINIDiE. 



the " Comptes rendus " for that year.* " The family of 

 Lucina,'''' he states, " is composed of mollusca which have 

 only a single branchial leaflet on each side of the visceral 

 mass, and of the foot. This single branchia resembles that 

 of the Anodonta ; it is large, thick, and formed of pec- 

 tinated and anastomosing lamellse." This pecnliarity was 

 first observed by M. Valenciennes in the Lucina Jamai- 

 censis, afterwards in Lucina tigerina (so long considered a 

 Venus or Cytliered) ; also in Lucina columhella and in 

 Lucina lactea. An examination of the animal of Corhis 

 shewed that it also presented this curious feature, but was 

 distinguished from Lucina by its non-perforated foot. He 

 further discovered that in the Lucina. the aperture of the 

 mouth is very small, and surrounded with weak and thin 

 folds of skin, being rudimentary lips. He confirmed the 

 statements of Poll respecting the singular structure of the 

 foot, and completed his description. " This foot," he states, 

 " is a fleshy cylinder, folded back on itself so as to be 

 hidden between the plates of the mantle of the mollusk, for 

 it is frequently twice as long as the diameter of the animal. 

 When not contracted, it is much longer. It is remarkable, 

 that it is hollow throughout its entire length, and that this 

 tube opens directly and widely into the spaces of the 

 visceral cavity." There can be little doubt that the single 

 gill accorded by M. Valenciennes is an organ similar to that 

 observed by Professor Owen in Pholadomya and Aimtina, 

 viz., the two lamellae of the same side so united as to 

 appear like a single gill. 



In conformity with general opinion, we place the genus 

 Diplodonta, the species of which closely resemble, and were 

 formerly associated with Lucina in this family, though, as 



* See also " Annals of Nat. History," vol. xvi. p. 41, where the paper is well 

 translated. 



