LA.MELLIBRANCHIATA. 67 



and obsoletely plicated above, posterior end pi'oduced, sub-angular, 

 slightly folded; lateral teeth obsolete. Height, l - 4; length, 22. 



Common. 



The Natives call this shell " hohe-hohe." 



41. T. deltoidalis, Lamarfc, vi., p. 206. Ovate, thinnish, white, 

 very finely concentrically striated ; anterior end rounded ; posterior 

 rather produced, sub-angular, strongly folded ; right valve with tAvo 

 cardinal teeth, the posterior bifid, and a small lateral tooth on each 

 side ; left valve with one bifid cardinal tooth. Height, 1'4; length, 1/75. 



Abundant. Stewart's Island. 



42. T. SUblentiCUlariS, Sowerly ; T. lactea, Gray, I.e., ii., p. 

 254, ex parte. Sub-orbicular, rather thick, strongly concentrically 

 striated ; anterior end rounded ; posterior end shorter, very obtusely 

 sub-angular, slightly folded ; right valve with two slight cardinal and 

 one strong lateral tooth on each side ; left with two cardinal teeth, and 

 a notch on the hinge plate near the posterior end of the ligament. 

 Yellowish white, umbones yellow, interior white round the margin arid 

 bright yellow between the muscular impressions and up to the umboues. 

 Height, 1*5 ; length, 1'5. 



Chatham Islands. 



43. T. deCUSSata, Lamark, vi., p. 205. Sub-orbicular, thickish, 

 rather strongly concentrically and finely transversely striated ; anterior 

 end rounded ; posterior end shorter, obtusely sub-angular, scarcely 

 folded ; right valve with two and left valve with one bifid cardinal 

 tooth, lateral teeth obsolete. White. Height, '57 ; length, - 7. 



West Coast of the South Island. 



44. T. lintea, sp. nov. Oval, thin, pellucid, very finely concen- 

 trically and transversely striated ; anterior end rounded, posterior end 

 longer, sub-angular, scarcely folded ; right valve with two and left 

 valve with one cardinal tooth ; lateral teeth obsolete. White. Height, 

 6 ; length, '82. 



Stewart's Island. 



* 45. T. SllbOVata, Sowerby. Shell snow white, half pellucid, 

 equally compressed, rather squarely ovate, smooth, not flexuous ; pos- 

 terior side rather short, with the dorsal margin sloping, truncated at 

 the end ; posterior angle nearly obsolete ; ventral margin rather 

 straight ; anterior side oblong, dorsal margin sloping, excavated near 

 the umbones, very obtusely angular at the end ; cardinal teeth small, 

 no lateral teeth ; ligament partly imbedded. (Reeve.) 



46. T. ticaonica, Deshayes, Proc. Zool. Soc., 1854,^?. 358. Oval, 

 thin, pellucid, smooth, compressed, anterior end rounded ; posterior 

 shorter, obliquely truncated, sub-angular, folding obsolete. Pale 

 yellow or rosy pink. Height, - 3 ; length, - 5. 



Stewart's Island, 14 fathoms. Australia. 



MESODESMA. 



Oval or sub-trigonal, thick, compressed, closed ; ligament internal, 



