80 CONCHIFERA. MONOMYAIRA. 



with two strong teeth in each valve, and a hollow between 

 for the ligament, which is internal. 



P. ramosa, Lam. (S. plicalus, Lin.) Shell oblong, trigonal, very 

 thick, plaited longitudinally ; colour whitish,, pale brown, reddish 

 or yellowish, with ferruginous lines. 2 inches long. Inhabits Ameri- 

 can seas. them. vii. pi. 47, fig. 479, 480. 



Several species of this genus are found fossil in Britain. 



Gen. 18. PECTEN, Lam. Ostrea, Lin. 



Shell free, regular, eared ; beaks approximate ; hinge without 

 teeth ; ligament internal, in a triangular cavity. 



The shells of this genus are in general of a depressed form, more or less inequi- 

 valve, always eared, and almost always rayed longitudinally by ribs more or less 

 fine. The valves are in general thin, of the same size, and the upper valve flattened. 

 The species are numerous, and the greater portion of them ornamented with various 

 and often brilliant colours. Aristotle relates that the Pectines have the power of 

 removing themselves from place to place by long leaps ; and the observation of this 

 ancient naturalist has been since confirmed. A basket full of the common Pecten 

 placed at the edge of the water has been seen speedily emptied by the individuals 

 springing from their confinement to their native element. This is effected by the 

 sudden opening and shutting of the valves, the lower striking against the part of 

 support below, and acting as a spring. Scallops were formerly worn by pilgrims 

 in their hat or the cape of their coat, as emblematic of their having crossed the sea 

 in their way to the Holy Land, or to some distant object of devotion. The fossil 

 species of this genus are very numerous, and in various strata. 



* Ears equal or almost equal. 



P. maximvs, Lam. Shell with about fourteen rounded longitudi- 

 nally striated ribs, and the upper valve impressed between the 

 auricles ; under valve whitish, upper valve variegated with brown. 

 5 inches long. European seas. B. Brown's Illust. pi. 32, fig. 1. 

 The hollow valve of this species, the largest native one, was formerly used as a 



drinking cup, and is still used in the Hebrides, where it abounds, for a similar purpose. 



P. Jacobceus, Lin. Shell with from fourteen to sixteen angulated 

 ribs ; the lower valve white, and longitudinally sulcated ; upper 

 valve rufous. 2 inches long. Inhabits coasts of Europe. B. 

 Browns Illust. pi. 33, fig. 5. 



P. glaber, Lam. Shell suborbicular, with about ten slightly ele- 

 vated ribs, the alternate ones smaller, and longitudinal striae in 

 the interstices ; colour various. 1-J- to 2 inches long. Inhabits 

 Mediterranean sea. Bonan. 2 fig. 12. 



** Ears unequal. 



P. nodosus, Lam. Shell with nine rounded ribs and strong longi- 

 tudinal striae ; ribs armed with hollow vesicles on the upper 

 valve ; colour red, or variegated with red and white. 2 to 5 in- 

 ches long. African and American seas. D'Argenv. pi. 24, fig. F. 



P. opercularis, Lam. Shell orbicular, with about twenty convex 

 ribs, and crowded decussated striae ; upper valve more convex than 

 the lower. 2 to 3 inches long. Inhabits European seas. Very 

 common. B. Pen. Brit. Zool. iv. pi. 63, fig. 2. 

 This shell, one of the most common, is also one of the most beautiful native spe- 

 cies. It is found extremely various in point of colour and markings, from pure 



