113 



PEDUM. 



OSTREA SPONDYLOIDEA. Gmeltll. 



Sowerbys Genera, No. 2, pi. 1. I 

 The G. Pedum, from the singularly sloping notch in the 

 lower valve, for the passage of the byssus, evidently is 

 allied to the G. Avicula, and G. Meleagrina; it also in- 

 dicates the approach of the G. Plagiostoma and G. Li- 

 ma, though very distinct from either. The shell is of 

 a regular form, its lower valve, in which is a sinus for 

 the byssus, is turned up at the margins, being thick- 

 ened and angular, and somewhat resembles a fire shovel 

 in shape; the upper valve, the edge of which is smooth 

 and sharp, without any angle, falls within the lower. 

 Hinge without teeth, and the ligament connecting it 

 partly exterior, as in the Spondylus. The French tri- 

 vial name for this shell is La Houlette, from its resem- 

 blance to their shepherds crook or hoe. Shell inequi- 

 valve, a little eared*, inferior valve gaping, apices dis- 

 tant and unequal ; hinge without teeth ; ligament part- 

 ly external, placed in a lengthened deep narrow groove, 

 cut in the internal division of the summits, the lower 

 valve sloped near its posterior base. Upper valve with 

 i 



