224 KELLIIDvE. 



and the Sphceriida possess the peculiarity of their tube 

 or tubes being situate at the shorter and smaller side of 

 the shell, which may therefore be considered the pos- 

 terior end, the ligament being situate at the other end. 



Philippi described the present genus under the name 

 of Bornia, though not without some suspicion of its being 

 identical with Kellia. He remarks that he had no 

 means of seeing Turton's work on the British bivalves. 

 One character of his genus he conceives to be of very 

 great importance j and that is the absence of any mark 

 of a fold of the mantle — " sinus palliaris nullus." There 

 must be some mistake in this. The character exists in 

 Mediterranean as well as in British examples of the 

 typical species. Perhaps Philippi meant to say that the 

 pallial scar in Kellia is not sinuated as in the Veneridce 

 and allied families. 



It may be well here to say that, in describing the right 

 and left valves, I have followed the rule laid down in 

 Dr. Gray's " Conchological Observations" (Zool. Journ. 

 i. p. 208), viz., "When a bivalve shell is placed on its 

 basal margin, with the ligament towards the observer, 

 the right and left valve will correspond with his own 

 sides." Some rule of this kind is indispensable, in 

 order to ensure a uniform method of description ; but it 

 appears of late years to have been left to the caprice of 

 every author. 



Many species of Kellia are known in a recent and 

 fossil state. During the formation of the Crag strata, 

 within the area which is bounded on the west by the 

 counties of Norfolk, Suffolk, and the adjacent corner of 

 Essex, several kinds nourished ; but of these one only is 

 known to have survived, and still exists in the British 

 seas. 



