12 



OBSERVATIONS. 



I received this shell from Mr. T. R. Peale, who 

 found several specimens at the mouth of a river o^ 

 the coast of Maine. 



This species is related to P. Islandicus, and has 

 sometimes been confounded with it, but differs in 

 having much fewer ribs, which are large, very ru- 

 gose, and have few scales : the ribs of the former spe- 

 cies, on the contrary, are small and densely furnished 

 with erect scales. On none of the specimens collect- 

 ed by Mr Peale was any trace of those curious reticu- 

 lated lines which are observed on a beautiful Pecten 

 from the eastern coast, which has also been confound- 

 ed with the present species, although the resemblance 

 is only in the outline. 



It is probable that this species, like some of its con- 

 geners, lives only in deep water, and is therefore sel- 

 dom cast ashore by the surf in the most violent storms. 

 P. Magellanicus is a remarkable instance of a shell 

 abundant it deep water, and very rarely found cast 

 upon the beach. 



PECTEN ORNATUS. 



Tab. II, fig. 3. 



SPECIFIC CHARACTER. 



Shell subequivalve, compressed ; ribs 30 to 36, 

 alternately smaller, and subscabrous; one ear mi- 

 nute. 



