Chione.] PELECYPODA. 9<)1 



4. Chione crassa, Quoy and Gaimard, 1835. Plate 62, fig. 4. 



Venus crassa, Q. & G., Voy. Astrol., iii, 1835, 525, pi. 84, f. 7, 8. V. spissa, 

 Deshayes, A.s.V., ed. 2, vi, 373 (niis])rint for crassa). V. crassa, Q. & G., 

 Dieff. N.Z., 250. Chione ijibbosa, Button, O.M.M., 71 ; J. cle Conch., 

 xxvi, 49 ; M.N.Z.M., 148. Vi'ims yibbosa, Butt., Plioc. M., 81, pi. '.. 

 f. 88. C. crassa, Q. & G. : Suter, P. Mai. S., vi, 203 ; E. A. Smith, 

 op. cit., 20(i. 



Shell rather small, triangularly orbicular, globose, subequilateral, 

 very thick, with concentric thick ribs, light brown, occasionally with 

 2 darker radial bands. Beaks approximate, slightly anterior, swollen, 

 incurved and turned forwards, sharply pointed. Anterior end a little 

 shorter, very narrowly convex, the dorsal margin very oblique and 

 slightly concave ; posterior end narrowly rounded, the dorsal margin 

 descending, faintly convex ; ventral margin regularly convex. 

 Lunule large, ovate, striated. Escutcheon slightly excavated, narrow, 

 finely striated. Sculpture consisting of numerous rather broad, 

 depressed concentric ribs, with a sharp upper edge and finely con- 

 centrically striated, the interstices very narrow ; faint dense radiate 

 striae are generally present. Colour whitish, yellowish-white, or light 

 brown, sometimes with 2 darker radial bands descending from the 

 umbo to the middle and posterior part of the ventral margin. Interior 

 white, bordered by dark violet. Margins finely crenulated. Hinge 

 strong, broad, short ; right valve with 3 cardinals, the anterior lamellar, 

 oblique ; the median vertical, the posterior oblique, both moderately 

 strong ; left valve also with 3 cardinals, the median slightly grooved, 

 the posterior tooth long, thin, and very oblique. Ligament narrow 

 and short, inset. Adductor-scars almost equal, ovate. Pallial sinus 

 short, triangular, free, and ascending. 



Length, 27 mm. ; height, 24-75 mm. ; diameter, 18 mm. (type). 

 Type in the Mus. Hist. Nat., Paris. 



Hab. Preservation Inlet ; Stewart Island, in 18 fathoms ; off 

 Wreck Reef, in 65 fathoms ; Auckland Islands (Captain Bollons). 



Remarks. This species does not represent old and thickened 

 shells of C. mesodesma, for in young shells the proportion between 

 length and diameter is about the same as in adult shells. The form 

 of the lunule is always different in the two species. 

 Fossil in the Pliocene. 



5. Chione mesodesma, Quoy and Gaimard, 1835. Plate 62, fig. 5. 



Venus mesodesma, Q. & G., Voy. Astrol., iii, 1835, 532, pi. 84, f. 17, 18 ; 

 Dieff. N.Z., 251 ; Button, P.L.S. N.S.W., ix, 523. Chione mesodesma, 

 Q. & G., C.M.M., 70 ; J. de Conch., xxvi, 49 ; M.N.Z.M., 148 ; Chall. 

 Rep., xiii, 131 ; Suter, P. Mai. S., vi, 204. Venus crassa, Q. & G. : Suter, 

 T.N.Z.I., xxxiv, 221 ; not of Q. & G. Chione crassa, Q. & G., Index, 39 ; 

 not of Q. & G. ? Venus spurca, Sowerby, P.Z.S., 1835, 23 ; Thes. Conch., 

 ii, f. 92-97 ; Conch. Icon., xiv, f. 90. Murcia scansitis, Romer, Mai. 

 Blatt,, vii, 1860, 161. 



Shell small, oval, subtrigonal, rather compressed, subequilateral. 

 concentrically closely ribbed, whitish with radial bands or zigzag lines 



