52 DENTALIUM-ANTALIS. 



Sacco recognizes ' varieties ' pseudaprina, mutabilis, incequicostala 

 decemcostata, undecemcostata, duodeeemcostata and tredecemcostata in 

 the Italian Pliocene. They are probably mere forms, and may be- 

 long to the closely allied D. incequicostatum Dautz. 



D. IN^QUICOSTATUM Dautzenberg. PI. 9, figs. 49, 50, 51. 



Shell moderately or slightly arcuate, either decidedly or slightly 

 tapering, very solid, nearly lusterless. Whitish, with numerous ill- 

 defined orange-red or roseate zones, and suffused with that color to- 

 ward the apex. Sculpture of 9-12 strong primary ribs toward the 

 apex, narrower than their intervals, which are smooth except for 

 very faint, close longitudinal striation, and rather conspicuous 

 growth-strise ; smaller secondary ribs, alternating with the others, 

 soon appear, and toward the aperture, where the sculpture becomes 

 weaker, some tertiary cords ; so the ribs are rather irregularly alter- 

 nating in size ; adults showing some irregular, shallow or deep con- 

 strictions around the tube, caused by interrupted growth or break- 

 age. Aperture subcircular, slightly polygonal, somewhat oblique. 

 Apex wide and truncate in adults, with a small, short central tube. 

 No slit or notch. 



Length 50, diam. of aperture 4*5, of apex 2 mill. (Specimen). 



Length 35, diam. of aperture 5 mill. (B. D. & D.). 



Mediterranean, from Greece and Sicily to southern France, Algeria 

 and Tunis ; laminarian zone. 



D. dentalis LAM., An. s. Vert., v, p. 344. Risso, Hist. Nat. Eur. 

 Merid., iv, p. 398. DESK., Mem. Soc. H. N. Paris, ii, p. 353, pi. 16, 

 f. 9, 10. PHILIPPI, Enum. Moll. Sicil., i, p. 243 ; ii, p. 206. JEF- 

 FREYS, Ann. Mag. N. H., 1870, p. 10. MONTEROSATO, Not. int. 

 alle Conch. Medit., p. 28; Conch, delle Rada di Civitavecchia, p. 8. 

 Not D. dentalis Linne. 



D. fasciatum LAM., 1. c., p. 343. Not D. fasciatum Gmel. 



D. novemcostatum Lam., PAYR., Moll, de Corse, p. 19. JEF- 

 FREYS, Moll. Piedm. Coast, p. 26. WEINKAUFF, Conch, des Mit- 

 telm., ii. p. 420. MONTEROSATO, Norn. Gen. e Spec., p. 31. Not D. 

 novemcostatum Lamarck. 



? D. striatulum DE BLAINV., Diet. Sci. Nat., xiii, p. 70 (1819). 



D. pseudo-antalis SCACCHI, Catal. Conch. Reg. Nap., p. 17 (1836). 

 Not D. pseudo-antalis Lamarck. 



D. alternans BUQ., DAUTZ. & DOLLF., Moll. Mar. du Roussilon, 

 i, p. 561, pi. 66, f. 7, 8, 9. Not D. alternans Chenu. 



