4S( ) Transactions. — Geology. 



Bouchardia tapirina. Plate XLVI., fig. 6. 



Wald. tapir ina, Hutton, Cat. Tertiary Moll, of N.Z., p. 36. 



Wald. sp., Hector, Outlines of Geol. of N.Z., p. 56, f. 8. 



Shell suborbicular, smooth ; valves depressed, nearly 

 equally convex. Beak produced, slightly curved, laterally 

 keeled. Foramen minute ; deltidial area large and solid. 

 Interior unknown. 



Length, 22-40 mm. ; width, 20-36 mm. ; thickness, 13- 

 16 in ni. 



Localities. — Mount Somers limestone ; Curiosity Shop ; 

 Oainaru. 



B. zittelli, Jhering, from Santa Cruz in Patagonia, differs 

 in having a well-marked anterior sinuation. 



Bouchardia rhizoida, sp. nov. Plate XLVI., fig. 7. 



Shell ovato-pentagonal or oval, longer than wide, smooth. 

 Dorsal valve more inflated posteriorly than the ventral, but 

 anteriorly they are equally flattened. Commissure nearly 

 straight. Beak much produced, slightly incurved, laterally 

 keeled ; foramen small ; deltidium large, triangular, solid. 

 Interior unknown. 



Length, 32-44 mm. ; width, 24-32 mm. ; thickness, 17- 

 23 mm. 



Localities. — Weka Pass district (type) ; Oainaru. 



Distinguished from the last species by its shape and 

 greater thickness. 



Rhynchonella nigricans. 



B. nigricans, Sowerby, Davidson, Proc. Zool. Soc. 1872, abstr., 

 p. 7, pi. i., figs. 30, 31 ; Suess, Reise der " Novara," Palae., 

 p. 60, taf. xiv., fig. 4. 



Shell thin, wider than long, but very irregular in shape ; 

 margin crenulated, commissure sinuated. Longitudinal ribs 

 about 20-25 in each valve. 



Length, 19 mm.; width, 21mm.; thickness, 10 nun. 



Localities. — Wanganui ; Curiosity Shop. 



Rhynchonella squamosa. 



B. squamosa, Hutton, Cat. Tertiary Moll, of N.Z., p. 37 ; 

 Tate, Phil. Soc. Adelaide, 1880, p. 27, pi. ix., fig. 9. 

 B. nigicrans, var. pixydata, Davidson, " Challenger Re- 

 ports," vol. i., p. 59, pi. iv., f. 14. 



Shell irregular, more or less orbicular, generally trans- 

 verse. Valves unequal, the ventral flatter and with a deep 

 sinus; dorsal valve very convex; both with fine radiating 

 scaly stria?. 



