956 PELECYPODA. [Eulamrllibranchia . 



1. Leptomya lintea, Hutton, 1873. Plate 54, tig's. 14. c. 



Tellina decussata, Lamarck : Hutton, C.M.M., <i7 ; not of Lamarck. 

 T. lintea, Hutton, op. cit., 67. T. subovata, Sowerby : Hutton, op. cit., 

 67; J. de Conch., xxvi, 47; M.N.Z.M.. 144: P.L.S. N.S.W., ix, 521, 

 not of Sowerby. T. 8tranciei, Deshayes : Hutton, J. de Conch., xxvi, 

 47 ; M.N.Z.M., 144 ; Plioc. M., 80 ; Index, 91, not of Deshayew. Lepto- 

 mya lintea, Hutton : Suter, P. Mai. S.. vii. 1907, 213, pi. 18, f. 10. 



Shell oval, thin, somewhat pellucid, more or less inequilateral, 

 angular behind, concentrically and radially striated. Beaks promi- 

 nent, approximate, curved inwards. Anterior end regularly rounded, 

 the dorsal margin straight, very little descending ; posterior end 

 narrowed, sometimes a little longer, subangular, slightly folded, the 

 dorsal margin convex, oblique ; basal margin broadly rounded. 

 Lunule clearly defined, lanceolate, with oblique sublamellar folds, 

 devoid of radiate sculpture. Escutcheon ill defined. Sculpture con- 

 sisting of fine subequidistant concentric strife, with better-marked 

 periods of rest, sometimes lamellar at the posterior end. where a 

 distinct fold runs down from the beaks ; this concentric sculpture 

 is reticulated by exceedingly fine 1 and close-set radiate stria-. Epi- 

 dermis thin and light-yellowish, easily rubbed off. Cohur mostly 

 white, sometimes inconspicuously banded with darker and lighter 

 yellowish-brown. Interior white, porcellanous, the margins smooth. 

 Hinge-plate narrow and short ; the right valve with '2 simple slightly 

 triangular cardinals, the anterior oblique ; posteriorly a narrow and 

 very oblique resilium ; left valve with I stout bifid or trifid car- 

 dinal, in front of which is sometimes, but not always, a small lateral 

 tooth. Ligament short, with very slender nympha 3 . The anterior 

 adductor-scar is oblong, not very distinct, the posterior scar round 

 or oval, and well impressed. Pallial sinus deep and broad, rounded 

 in front, not coalescent at the base with the pallia! line. 



Length, 25 mm. : height. 17 mm. ; diameter, 10 mm. (from 

 Stewart Island). Length. 14 mm. ; height, llmm.; diameter. 6mm. 

 (from Auckland). 



Type in the Dominion Museum, Wellington. 



Plab. Stewart Island (type) ; Banks Peninsula ; Petane ; Hau- 

 raki Gulf, from low-water mark to 25 fathoms ; Manukau Harbour. 



Fossil in the Pliocene. 



Fam. MESODESMATIDJE, Deshayes. 



Animal having the external branchial plate directed ventrally ; 

 siphons separate and equal ; foot large, triangular, not byssiferous. 



Shell solid and heavy, usually Donaciform, equivalve, not gaping ; 

 with erect or opisthogyrate beaks ; hinge usually with a cardinal 

 tooth in each valve in front of an internal central resilium ; lateral 

 teeth almost always well developed anteriorly and posteriorly ; ad- 

 ductor-sca-rs deeply impressed ; pallia! line sinuous or simple. 



Tertiary to Kecent. 



