Conus bonus       (Nomura, 1935)

 

 

 

 

Descrizione.

 

Shell  medium  in  size,  elongate conic;  test  rather  thin.     Spire   short,   outline   nearly straight, or slightly concave, acutely pointed at top of spire. Whorls about 12, apical ones smooth, globular, embryonal; rest more or less concave with peripherial angle projecting above suture; angles on upper (about 5 whorls) whorls minutely beaded or crenulated, those on lower ones almost smooth. Spirally striate; striae rather unequal, 4-5 between suture and angle, crossed by fine oblique growth lines. Body-whorl almost straight in lateral outline, acutely angulated at periphery; densely and spirally grooved, or ridged throughout, grooves stronger on lower one-third than upper two-thirds; aperture narrow, obliquely straight, sides parallel.

Three beautifully preserved specimens; one figured, 42,5mm. in height, 20,5mm. in dia­meter, and 36,5 mm. in length of aperture.

In form, this shell resembles the recent Japanese species C. sieboldi REEVE, but it cer­tainly differs from that species in the surface sculpture. The Formosan fossil has spirals which are finner, more numerous and cover the entire surface, while C. sieboldi is said to have only a few distant grooves on the basal part of the body-whorl.

C. sieboldianus MAKIYAMA is a smaller shell with a more elongated spire, and has a slightly different ornamentation.

 

Fossil occurrence: Byoritu Beds,—Wangwa: station 24; Reg. No. 52393. Wangwa: sta­tion 33; Reg. No. 52581.

 

Pliocene, Taiwan.

 

 

 

Conus bonus

NMNS000334-F000381

mm. 24 x 12

 

 

 

 

 

 

Bibliografia

 

·         (1) Nomura, S., 1935. Catalogue of the Tertiary and Quarternary Mollusca from the Island of Taiwan (Formosa) in the Institute of Geology and Palaeontology, Tôhoku Imperial University, Sendai, Japan Part 2, Scaphopoda and Gastropoda. Sci. Repts. Tôhoku Imp. Univ. Sendai., 18 (2 ): 53 -228

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