103 



Xew Zealand : Two left valves of an unnamed " Ostrea, Xo. 

 175, from Oamaru Creek, Otago," received from the AYelling- 

 ton Museum, are comparable with the triangular-ovate form of 

 P. sella. The two subcentral muscular scars so characteristic 

 of the genus are well displayed. 



FAMILY PECTINID.E. 

 Gsxrs Pectex. 



STIs'OPSIS OF SPECIES. 



I. Eadially ornamented. 



1. luequivalve, interspaces with shagreen-sculpture. 

 Eight radial folds and many riblets. P. consohrinus. 

 Twelve truncated ribs. P. siibhifrons. 

 Seven broad plications or compressed plicae. F.iyalmipes. 



2. Inequivalve ; no shagreen- sculpture. 



Eibs simple. P. Murrayamis. 



nibs dichotomously divided. P. dichotomalis. 



3. Equivalve ; radial ribs more or less scaly. 



Eibs 25, flatly rounded, one or two riblets on each 

 flank. P. antiaicstralis^ 



Eibs 25, rounded, broader than interspaces, densely 

 squamose. P. JEyrei.. 



Eibs 35-40, flatly rounded. P. Flindersi. 



Eibs 35-40, acute ; one riblet on each flank. P. Peroni. 



Eibs 30, flatly rounded equal to the furrows. 



P. Sturtianus^ 



Eibs 50, narrow ; oblique-linear sculpture in the inter- 

 spaces. P. Aldingensis. 



Eibs 60-70, very narrow. P. Tahlensis. 



4. Eadially plicate and ribbed with spinose ornament. 

 Plat ; plicae 9, intermediate ribs 9. P. Foulcheri, 

 Inflated ; plicae 7-9, intermediate ribs 7-9. 



P. spondyloides. 



5. Eadially plicate and ribbed with scaly ornament. 

 Eadial folds 7-9, simple. P. Gambierensis. 

 Eadial folds bifurcating ; corrugated. F.polymorphoides 



II. Yalves smooth, or nearly so. 



Surface concentrically striated ; ears plain. 



P. Hoclistetteri . 

 Surface faintly rayed ; ears rayed. P. Yahlensis. 



III. Yalves with internal ribs. 



Yalves smooth or concentrically striated, internal ribs^ 

 30-36 pairs. P. lucens. 



Yalves concentrically or reticulatedly striated or 

 ribbed : internal ribs 9. P. Zitieli. 



