CONCHOLOGY. 81 



L.fragilis. The fragile Lima. 



Oblong ovale, very pellucid, delicately white, with longi- 

 tudinal distinct striae ; lower margin denticulated, closely in- 

 terlocking when the valves are closed. 



3. Pecten. The Scallop. Fifty-nine species. , 



The shells constituting this genus are found in all seas ; 

 they are well known, and many of them are very beautiful. 



The form is usually regular ; their surface is adorned 

 with elevated divergent ribs, varying in number from five to 

 thirty, proceeding from the beaks and terminating at the mar- 

 gins in a scalloped outline. 



Some are equivalve, others have one valve flat and the 

 other convex; the colours of the upper valve are brighter 

 than those of the lower. 



There is considerable variation in the size and form of the 

 ears, which in some species are equal or nearly so, but in 

 others are unequal ; some are so small as to be nearly in- 

 distinct. The ribs are variously diversified with beautiful 

 colours and delicate checker-work ; the margins are mostly 

 crenated, and oftentimes beautifully coloured. 



These shells were formerly worn by Pilgrims on their hat 

 or coat, as a mark of having been to the holy shrine in Pal- 

 estine. 



Shell free, regular, thin, solid, auricled, equivalve, equilat- 

 eral ; summits contiguous ; hinge without teeth ; a liga- 

 mental membrane through all the length of the hinge, be- 

 sides a short, thick ligament, almost entirely internal, which 

 fills a triangular cavity under the summits ; one sub-central 

 muscular impression. 



Pecten maximus. Pecten rastellum. 



P. medius. P. turgidus. 



P. Jacobaeus. P. flagellatus. 



P. bifrons. P. aspersus. 



P. ziczac. P. flavidulus. 



P. Latirentii. P. plica. 

 L 



