550 PECTINID.E. 



valves being sculptured, at present comprises but a single 

 recent species, from New Zealand. The denticles of the 

 anterior tooth extend in as numerous a series as those of 

 the posterior tooth, which is not the case in Malletia. 



Fam. PECTINIDiE. 



Mouth surrounded by foliaceous leaflets; labial palps 

 truncated, smooth externally, pectinated within. Mantle 

 freely open, the margins double, the inner pendent, bearing 

 fringes of tentacular filaments, and at its base a row of 

 eye-like spots or ocelli ; branchial leaflets equal, each pair 

 partially doubled on itself. Foot small, cylindrical, with a 

 byssal groove. Sexes united. 



Shell free, auricled. Ligament wholly or partially in- 

 ternal, lodged in a cardinal groove. Adductor muscles 

 united, leaving a single impression in the shells. 



Genus PECTEN, Linnteus. 



Shell oblong or sub-orbicular, regular, equivalve, closed ; 

 surface of valves usually with radiating scaly ribs; beaks 

 approximated; anterior auricles the larger, the right one 

 with a byssal sinus. Hinge-line straight; ligament mar- 

 ginal, linear ; cartilage central, lodged in a triangular pit. 

 Muscular scar large, sub-central ; pallial line entire. 



Syn. Argus, Poli. 



Ex. P. varius, Linnaus, pi. 127, fig. 1. Shell, P. pal- 

 lium, Linnaus, fig. 1, a, 1, b. 



The foot in these animals is not adapted for crawling, 

 but is used chiefly as an exploring organ, and to anchor 





