174 i HITON. 



are rather stronirlv arrhed hack ward, and the broad sinus is remark- 

 able for the absence or obsolescence of teeth. The interior, except 

 just behind the .-inns, is smooth ; the callus in each valve is heavy 

 and smooth. Figures 14, !>, 17 arc drawn from Auckland, X. /. 

 examples, furnished by Mr. < J. W. Wright. 



C. SINCLAIRI Gray. PI. 36, figs. 1, 2, 3. 



Shell oval, rather elevated, the dor*l ridge rounded, side-slopes 

 rather straight; brown-black, each valve irregularly and raggedly 

 Hh whiti*h; the head valve pale with dark rays. Some- 

 times the white predominates. 



The lateral areas are raised and sculptured with three or four 

 i-'id luting granoe rib*, often *nbobsolete. Central areas xmooth in the 

 middle except for a few growth-wrinkle*, but having fine .hort lougitu- 

 <> the ."life." in front of the diagonal line. These riblets 

 are sometimes almost obsolete. Head-valve sculptured at first with 

 about 15-18 granose riblets, but as these have a tendency to split as 

 the valve grows, the number in a grown specimen is usually 24-30. 

 Tail-valve having a low, obtuse mucro, decidedly in front of the 

 middle. 



Interior bluish. Sinus rather wide, denticulate, the area behind 

 it porous. Anterior valve having 11, central valves 1, posterior 

 valve 14 slits; teeth obtuse, strongly crenulated. Eaves broad, 

 _y. 



Girdle (pi. 36, fig. 3) covered with large, convex scales, which 

 are very finely, sharply striated. 



Length 28, breadth 18 mill. 



Length 17, breadth 11 mill. 



New Zealand (Sinclair, Hutton, Wright.) 



Chit"n ."'nn-lnu'i ClHAY, in Dieftenbach's Travels in N. /. ii, p. 263 

 (1843). HUTTON, Trans. N. Z. Inst. iv, p. 177 ; Man. X. /. Moll. 

 p. Ill n.sO). SMITH, Zool. ' Erebus' and 'Terror,' p. 4. t, 1, f. 

 17. REI-:VE, Conch. Icon., t. 22, f. 143. 



The smooth, polished central areas, grooved only al..ii'j the 



nal line at t he sides, and the granoa6lii>bed lateral area< and 



en 1 valves are characteristic, and remind one of the \Ye.-t Indian ( '. 



The black-and-white coloring also is rather constant. The 



ivas varies greatly in stn-n^th. This s-pecies 

 has been reported from Tasmania, but mi doubtful authority. 



