960 PELECYPODA. [Eularnellibratichin. 



Subgen. 3. PAPHIES. Lesson, 1830. 



Paphies, Lesson, Voy. Coq., ii, 1830, pt. 1, 424. Macitctna (Leach, MS.), 

 Gray, 1843. Mesodesma, Auct. Pnphia, Button, 1885 ; not of Lamarck. 

 Type: MI/H itiixtrtiiix. Ginelin. 



Shell elongated, subequilateral, subsoleniform, solid : hinge con- 

 centrated, heavy ; laterals smooth or finely granulose. short ; liga- 

 ment short, mostly internal, small ; resilium narrow, vertical ; the 

 chondrophore projecting ; pallial sinus very small, angular. 



New Zealand only. 



3. Mesodesma australe, Umelin, 1790. Plate 59, fig. 17. 



M>/ii ii/irn ---.I iliindicK, Chemnitz, Conch. Cab., vi, 1782, f. 19, 20; not binomial. 

 Mi <></< xn/ii novce-zeelandice, Chemn.. Conch. Icon., viii, 1854, f. 21; 

 Ad. G.R. M., ii, 413, pi. 106, f. 2; C.M.M., 68; Crit, List, 43: Hutton, 

 .1. ilc Conch., xxvi, 48; M.N.Z.M., 145. Paphia neozdnnifu. Chemn.: 

 Hutton, i'.L.S. N.S.W., ix, 519. Myn <inxtrul>s, Ginelin. Syst. Nat., 

 ed. 13. 1790,3221. Mesodtxniii australis, Gmelin : Hedley, Bull. Colon. 

 Museum, No. 1, 1905 (1906), 48 ; Suter, T.N.Z.I., xxx viii, 319. Paphies 

 Roi**!i<i>i(i, Lesson, Voy. Cocj., ii. 1830, 424. pi. 15, f. 4. Mesodesma 

 Ghent nitzi, Deshayes, Kncy. Meth., ii, 1831, 443 ; Voy. Astrol., iii, 1835, 

 504, pi. 82, f. 9-11; Dieff. N.Z., 252; C.M.M., 68. M. subtriangulata, 

 Gray : Griffith and Pidyeon, " Cuvier's Mollusca," xii, 1834, pi. 22, f. 2 ; 

 not of Gray, 1825. M. ovalis, Deshayes, P.Z.S., 1854, 336 ; Conch. 

 Iron., viii, 1854. f. 7 : C.M.M., 68 : Crit.' List, 44 ; M.N.Z.M., 145. 



Shell moderately large, oblong-oval, transverse, solid, subequi- 

 lateral, rounded at both ends, convex, compressed towards the margin, 

 whitish. Beaks not prominent, convex, approximate. Anterior end 

 sometimes a little longer than the posterior, narrowly rounded, the 

 dorsal margin straight, very slowly descending ; posterior end a little 

 higher, regularly rounded, the dorsal margin faintly convex, slowly 

 descending ; basal margin straight. Escutcheon not distinctly marked 

 < fl. Sculpture consisting of fine concentric lines, slightly lamellate 

 at the posterior end. Epidermis thin, horn-colour. Colour whitish, 

 very often with rust-stains at the dorsal anterior part. Interior 

 white, porcellanous, with faint radiate striation at the margins. 

 Hinge short and broad, heavy ; right valve with 1 thin and low 

 cardinal lamella in front of the resilifer and 2 lateral teeth in front 

 and behind, those near the centre very stout, minutely granulose, 

 the outer and upper ones very small ; left valve with a stout nearly 

 vertical cardinal and 2 strong oblique short triangular lateral teeth. 

 Kesilifcr vertical, narrow, much produced downward posteriorly. 

 Ligament feeble, internal, posterior, triangularly produced downward 

 behind the resilium and sometimes partly separated from it by a small 

 lamella. Adductor-scars deeply impressed, unequal, the anterior 

 smaller, pyriform, the posterior roundish. Pallial line deep, the 

 inner part of the disc very thick ; the sinus very small, triangular. 



Length, 60 mm. ; height, 35 mm. ; diameter, 21 mm. 



