356 GASTROPODA. [Pectinibranchia. 



1. Megalatractus maximus, Tryon, 1881. Plate, 18, fig. 1. 



iiiu.riiiiu. Try on, Man. Conch, (i), iii, 135, pi. .34, f. 355 : Medley, 

 Mem. A.M., iv, 1903, 374, pi. 38. Megalatractus maximus, Tryon : 

 .Murdoch and Suter, T.X.Z.I.. xxxviii. 2!>l. pi. 24. f. 28 (protoconch); 

 Suter, T.N.Z.I., xxxix, 254. ti>/rinz maxim.nx, Trvon : .Suter, Rec. 

 Canterbury Mus., i, Xo. 2, 124. 



Shell large, narrow fusiform, narrowly umbilicated. whorls angled 

 in the middle, canal long and open. Soil />//<,< consisting of flat-topped 

 spiral riblets parted by wide and shallow furrows with 1 or 2 fine 

 spirals ; the whorls of the spire sharply angled below the middle, on 

 the last whorl above the flattened periphery, the angle cut into 12 

 to 14 sharp projecting nodules ; the first two whorls below the nearly 

 smooth protoconch are distinctly axially costate. Colour : The New 

 Zealand specimens I have seen are uniformly light brown, but Aus- 

 tralian shells are ornamented with dark-brown spots and lines. Spire, 

 high, conic, gradate, a little higher than the aperture without canal. 

 Protoconch pupoid, polygyrate, consisting of 4 convex whorls with fine 

 spiral riblets, crossed by incremental lines, nucleus central, small. 

 slightly raised. Whorls 10 to 12, decollated shells have usually from 

 6 to 8 whorls, first slowly then more rapidly increasing, broadly 

 shouldered, the spire-whorls straight above and below the angle, the 

 body-whorl flatly convex below ; base excavated. Suture superficial. 

 Aperture, slightly oblique, ovate, porcellanous within, sharply angled 

 above, produced below into a long, broad, open canal, which is nearly 

 straight or flexed in an 8 curve slightly bent backward. Outer lip 

 distinctly angled, straight above, convex below, denticulate at the 

 edge by the spiral sculpture, lirate within. Columbia excavated, 

 broadly rounded, smooth. Inner lip spreading as a very thin glaze 

 beyond the columella and over the parietal wall, sharply drawn out 

 on reaching the inner margin of the canal, where there is a distinct 

 narrow umbilical fissure. Operculum oval, pointed at the apex, 

 with distinct growth-lines and a strong callus on the inner outer 

 side. 



Diameter, 68 mm. ; height, 145 mm. (decollated specimen of 7 

 whorls). According to Hedley. Australian specimens have a much 

 larger size, 100mm. by 237 mm. being recorded. 



Anatomy. Kesteven, Mem. A.M., iv, 419 5o. 



Type in the Museum of the Academie of .Science, Philadelphia. 



Hal). Near Channel Island, Hauraki Gulf, in 25 fathoms : off 

 Great Barrier Island, in 110 fathoms, one protoconch : New Brighton 

 Beach, one dead washed-up shell (H. S.) ; east of Jones's [lead, in 

 2<> fathoms ; west of Cape Runaway, in 105 fathoms (E. R. Waite). 



Remark. Sometimes the whorls are rounded, and there remains. 

 only a trace of the keel. 



Fossil in the Pliocene of Waikopiro. 



