Shells found in Essex County. 59 



Boston Journ. Nat. Hist., vol. ii., p. 64. I beg leave to dis- 

 pute its rarity, as the Society has in its possession very many 

 specimens, taken from the stomach of haddock, in the summer of 

 1838. 



Boston Journ. Nat. Hist., vol. ii., pi, iii. fig. 8, 

 JV. B. Strongly resembles Nucula concentrica. Say's Am. 

 Conchol., pi. xii., but which however is fossil. 



NUCULA MYALIS. Couthouy. Latin, like a mya. 

 Mya-like Nucula. 



A species of little beauty, first described by Couthouy, in Bos- 

 ton Journ. Nat. Hist., vol. n., p. 62, pi. cxi, fig. 7. "Shell 

 ovate, slightly gaping at both extremities, with numerous ridges 

 of growth teeth 20 to 22. Color, dull, yellowish white within; 

 epidermis dark olive." When this is worn off, the shell resem- 

 bles a young Mya or clam. A glance at the teeth, near the 

 beak, at once distinguishes it. 



Lynn beach. Cabinet of Dr. Wm. Prescott. 



UNIO. Jl Pearl, 



COMPLANATUS. Lea. Latin, flattened. 

 SYN. UNIO PURPUREUS. 



Purple Unio. 



Common in all the ponds of Essex Co., and occasionally of 

 much beauty ; though more or less eroded on the beaks. 

 Cabinet of the Society. 



Nicholson's Encyclopaedia, 3d Am. Ed., 1819, vol. iv, plate. 

 Very fine specimens of varieties have been collected by Dr. 

 Prescott, from Flax pond, Lynn, which would vie with any from 

 the Western States ; one, in particular, should be mentioned of 

 a most superb salmon, and were color of nacre alone sufficient 

 for specific distinction, it should be called Auratus, which I per- 

 ceive is a species of RarTinesque, and regarded as a synonym by 

 Conrad. Another is curious in having one valve purplish, and 

 its corresponding valve orange. Others with pure white nacre, 

 are of great beauty. 



