TRIBE BRACH10P0DA. 331 



well-defined lateral ridges ; perforation incomplete ; deltidia small ; 

 area flattened; lower valve rather flat; loop elongated, doubly 

 attached ; septum produced, nearly touching the opposite valve. £. 

 N. Zealand. 1 



T. Crenulata. Sow. Th. 1, p. 358, t. 71, /. 96, 7, 8.— Koch in 

 Kust. vii. ], t. 2, b,/. 11, 2, 3 ? — Terebratella C. Davids, (no desc). 

 — ? Magas C. Gray, Brack, p. 99. Suborbicular, inequivalve, rather 

 attenuated and subtruncated dorsally, rather thick, whitish, with a few 

 rather large rounded radiating ribs ; margin crenated, flexuous, slightly 

 sinuated ventrally ; perforation large, nearly entire ; hinge-area large, 

 flattish, with an undulated margin ; deltidia large, separate. Dorsal 

 edges of the lower valve sloping ; internal appendage consisting of a 

 single strong spine projecting towards the ventral margin, from whence 

 emanate two lateral reflected branches. T 7 T . Santa Cruz. 



T. Truncata.— Anomia T. Lm.1152.— G7i./701.— W. t.ll,f.l7. 

 —A. Disculus, Pallas. Mis. Z.—T. T. Lam. 11.— Phil. I, p. 95, t. 6, 

 /. 12 (in 2 as Orthis T.).—Sow. Th. 1, p. 354, t. 71, /. 64 to 67.— 

 Megerlia T. Gray, Brach. p. 103. — Woodw. 1. 15,/. 9. Transversely 

 suborbicular, subequivalve, depressed, truncated and very wide dorsally, 

 brownish, with a nearly straight hinge-line, and fine radiating striae : 

 margin entire, slightly sinuated ventrally. Perforation large, incom- 

 plete ; hinge-area elongated-triangular, flattened, with minute incon- 

 spicuous deltidia ; mesial ridge small. Lower valve rather flattened, 

 straight dorsally, with a small mesial notch; mesial groove rather 

 broad, not very distinct; loop short, doubly attached, and giving off 

 from its reflected portion two additional processes to the central 

 septum : internal surface with small close-set radiating granules. 



!_ 

 2 



1 This, the succeeding, and the Terebratella? Cumingii of 

 Davidson (Z. P. 1852, 1. 14,/. 10 to 16.— M. C. Gray, Brach. p. 99) 

 are referred by Gray (not by Davidson) to the subgenus Magas (of 

 Sowerby). The last-named species is thus described: — " Oval, thick, 

 smooth, white, slightly tinged with red ; beak produced, tapering, 

 slightly curved, grooved to the summit ; area triangular, concave ; 

 deltidium obsolete ; lower valve with a prominent muscular fulcrum ; 

 loop doubly attached; septum elevated, reaching the upper valve. 

 T 5 T ...y. N. Zealand. 



2 This and T. Pulchella are the only recent species of the 

 subgenus Megerlia. " Transversely oblong, with a wide and rather 

 straight hinge-line ; area distinct ; foramen incomplete ; loop rather 

 short, reflected, trebly attached to the hinge-plate, once by its crura, 

 and twice to the septum." 



