Notes on the Classification of the Corbiculadce, etc. 425 



fleshy, and thick. The interior surface of the external palpus, 

 and the exterior surface of the internal palpus, are marked by 

 oblique striae. The whole surface of the palpi is not covered 

 by these striae, the margin being perfectly smooth. The mouth 

 is quite broad, the lips and the balance of the digestive organs 

 are similar to those of Galatea. 



The abdominal mass is broad and high, and below it is com- 

 pleted b} r a foot, slightly angular in front, and rounded behind- 

 The foot of Corbicula is less high and less thick than that of 

 Galatea. 



Not having examined the entire nervous system, I can only 

 say that the branchial ganglion is very narrow. The arrange- 

 ment of the heart and of the vessels offers nothing worthy of 

 note. 



§ YII. — I deduce from this examination that the genus Cor- 

 bicula is very closely allied to the large family of " Les Con- 

 ques ; " the fact that the palleal impression is simple and not 

 sinuated, is not, in my estimation, reason sufficient for exclud- 

 ing it from this family. 



We have seen that the syphons exist, though in a rudimen- 

 tary state, and that the apertures of the mantle, and the con- 

 formation of the gills, are the same as in "Les Conques." 



"We have already remarked, in connexion with the genus 

 Galatea, that an examination of the anatomy of Psammobidee, 

 Donaciclse, Lithophagi, " Les Conques," and " Les Cyclades," 

 accepting these families as defined by Deshayes, shows no evi- 

 dence of any important differences in the structure of these 

 different families ; they all bear the impress of a similar orga- 

 nization. 



It is a matter of but little importance in which of the above 

 groups we place Corbicula and its kindred genera (Velorita, 

 Batissa, and Cyrena) ; I, myself, would place them near Galatea, 

 as their habits are similar, without even taking into considera- 

 tion that certain species of Galatea undergo such modifications 

 as to pass insensibly into one of the above genera. 



