OSTREA. 135 1 



the sixteen middle ones placed in fours ; that is, there are 

 four of these quadruple series between the grooves corre- 

 sponding with the rays on the outside, the two middle sets 

 of which are near together, the others being remote, the 

 color paler than the outside except near the hinge : length 

 three quarters of an inch ; breadth rather less. 

 Coast of Dunbar : very rare. 



1 1 . Ostrea obsoleta. Obsolete Scallop. 

 Pennant, pi. 64. f. 3 Donovan, pi. 1. f. 2. 

 Ostrea laevis. Linn. Trans, viii. pi. 3. f. 5. 



Shell somewhat orbicular or inclining to oblong, with 

 flat equal valves, yellowish or purplish-brown, often mar* 

 bled rayed or streaked with paler or darker colors ; the 

 surface sometimes quite plain, or with a few obscure trans- 

 verse wrinkles, but more generally marked on the lower 

 part with numerous rounded ribs, a smaller or greater 

 number of which are frequently more prominent and 

 placed at unequal distances ; and sometimes the upper 

 plain department is separated from the marginal ribbed 

 part by a strong depressed transverse line, the whole sur- 

 face being always marked with very numerous and most 

 minute longitudinal lines, which run rather obliquely to- 

 wards the sides, and are crossed by as fine transverse ones, 

 giving it a kind of shagreened appearance under a glass : 

 ears unequal ; the larger one with four or five strong 

 transverse ribs, and crossed by longitudinal transverse 

 wrinkles ; the other very small ; inside glossy, yellowish 

 or rich purple, finely striate longitudinally, with the mar- 

 gin slightly notched : length an inch 5 breadth not quite so 

 much. 



West of England, Scotland, and Dublin bay : v. m. 



B. Without ears, and the surface generally rough and 

 uneven. Oyster 13, 14. 



12. Ostrea edulis. Common Oyster. 



Lister, pi. 193, and 194 Pennant, pi. 65, lower fig. 

 Da Costa, pi. 11. f. 6 Dorset Cat. pi. 11. f. 6 Linn. 

 Trans, vi. pi. 18. f. 9, 10. 



Shell more or less orbicular, but subject to much varia- 

 tion of form size and bulk, often distorted and misshapen, 

 N rugged 



