194 DE. c. T. trechmajS-i^ OjS" [vol. Ixxiii, 



Freeh ealls var. innicata, ean also be identified among the New 

 Zealand shells (fig. 4). 



A small, dwarfed, and strongly-ribbed form, in which the right 

 valve is often strongly arched and bent downwards towards the 

 margin, very similar to the variety that Teller calls amhigua 

 (fig. 2), also occurs in association with all the other varieties. 



It ma}^ here be emphasized that I regard these different forms 

 as representing individual variants in one very variable species, 

 since some confusion or misuse of terms may arise in calling them 

 varieties. However, in describing the following form as var. 

 acutecostata nov., I am merely following the plan adopted by 

 Mojsisovics and Teller, who describe the specimens of different 

 shape from Verkhoyansk and Japan as varieties. 



Var. ACUTECOSTATA, nov. (PI. XIX, fig. 7.) 



The left valve is strongly arched, the beak is pointed, tapers 

 rapidly, and is acutely bent over the hinge-area. The outline of 

 the shell is angular, and there are about fourteen primarj^ ribs, 

 some of them very acute and prominent, others lower and more 

 rounded. Other very much sinaller secondary ribs appear about 

 halfway between the beak and the mai-gin. 



Locality and horizon. — Grarden Grully, south of the Wairoa 

 Gorge (Nelson), on the western slope of the valley, where all the 

 varieties occur. On the coast, south of Kawhia, towards Albati'oss 

 Point, where the varieties densistriafa and pacliyioleura occur. 

 Upper Noric. 



I collected a large series of examples at Garden Gully and 

 several at Kawhia. The Geological Survey possesses several 

 specimens of the different varieties from the Nelson district, 

 but the exact bed whence they came is not identified. 



Ke marks. — The geographical distribution of this form has 

 already been discussed. It has not yet been recorded from New 

 Caledonia. 



PSEUDOMOJs'OTIS EieHMONDiA:N-A Zittel. (PL XIX, figs. 9« & 95.) 

 1864. ' Palaontologie von Neu-Seeland ' p. 26 & pi. vi, figs. 1 a-1 e. 



This species has an oval and gently rounded outline, and the 

 margin is never angular as it is in some of the forms of Ps. 

 ocliofica, nor does the shell show the extremes of variation 

 exhibited by the individuals of that species. The byssal notch and 

 ear in the right valve are .small, but well developed ; the left valve 

 is gentl}^ arched and rounded, the right nearly flat. The ribs are 

 regular on both valves, being straight or slightly curved. Fainter 

 secondary ribs occur between the primary ribs, and commence a 

 short distance from the beak. There are about twenty-eight ribs 

 on the left valve. 



Freeh ^ describes a form under the name var. triincata, and 



^ Bibliograpliy, 13, p. 506 & pi. Ixviii, figs. 4c-4d. 



