Marshall. — Tertiary Molluscan Fauna of Pakaurangi Point. 273 



the umbo to the posterior truncation : this is much sharper in the left valve 

 than in the right. - Near the umbo the right valve is smooth or has very 

 small concentric striae. The concentric lines become more and more pro- 

 nounced as the ventral margin is approached. The sculpture of the left 

 valve is similar but somewhat less pronounced than that of the right. The 

 outer coating of the shell is frequently absent, and then leaves a perfectly 

 smooth and polished inner layer. 



A common species at Pakaurangi Point. Type in the Wanganui Museum. 



Pecten costato-striatus n. sp. (Plate XXII, figs. 1, 2, 3.) 



Shell small, slightly inequilateral, fan-shaped : height, 17 mm. ; breadth, 

 18 mm. Ears very unequal. Anterior ear large, nearly triangular, but 

 with the outer margin rounded. It bears 7 radiating ribs crossed by a 

 number of transverse bars which are almost spiny. The radiating ribs 

 which are near the hinge-line are much stronger than the others. Posterior 

 ear much stronger, smaller, with 5 ribs less strongly crossed by transverse 

 bars. Eight valve with about 40 rounded radiating ribs, many of which 

 subdivide into 3 each near the ventral margin. Each rib is crossed by a 

 large number of transverse striations : these are so deep as to almost make 

 the ribs appear to be composed of a large number of overlapping plates. 

 Towards the ventral margin these may develop into small spiny processes. 

 Interstices about as wide as the ribs, and crossed by a large number of fine 

 transverse lines. 



I am much indebted to Mr. Suter for examining this species, which he 

 rightly remarks is closely related to P. burnetii Zittel. This species is 

 perhaps the most abundant of the pectens at Pakaurangi Point. Type in 

 the Wanganui Museum. 



'■&'■ 



Pecten subconvexus n. sp. (Plate XXII, figs. 4, 5, 6.) 



Shell small, fan-shaped : height, 16 mm. ; breadth, 16 mm. : slightly 

 inequilateral. Ventral margin nearly circular. Ears unequal, the anterior 

 distinctly the larger with 6 radiating scaly ribs ; posterior ear relatively 

 small but with the same number of ribs, though they are less scaly and 

 less prominent than those of the anterior rib. The shell has a large number 

 of rounded radiating ribs. Intervening grooves usually much narrower 

 than the ribs, and both the grooves and the ribs are marked by a large 

 number of fine cross-lines. In some valves some 5 large radiating undu- 

 lations can be distinguished. 



Mr. Suter, who kindly examined these specimens for me, remarks that 

 the species is near to P. convexus Q. & G. This specie's is fairly abundant 

 at Pakaurangi Point. Type in the Wanganui Museum. 



Including the species described above, the following is now the com- 

 plete list of the species that I have found at Pakaurangi Point. Those 

 marked * are Recent species. 



Vaginella torpedo n. sp. 

 * Em arg 'inula striatula Q. & G. 

 Solar iella stoliczhai Zittel. 

 Calliostoma gracilis n. sp. 

 Astraea subfimbriata Suter. 

 Turritella semiconcava Suter. 

 Struthiolaria cincta Hutton. 

 Cerithiella fidicula Suter. 

 Crepidula gregaria Sowerby. 



*Calyptraea maculata Linn. 



Turbo etheridgei Ten. -Woods (?). 

 *Natica zelandica Q. & G. 



Polynices gibbosus Hutton. 



Ampullina suturalis Hutton. 

 *Trivia avellauioides McCoy. 



Cymatium minimum. Hutton. 



Epitonium browni Zittel. 



Epitonium trilineatum n. sp. 



