EAST AMERICAN SCAPHOPOD MOLLUSKS. 



47 



rib in each space usually occurs, but the secondary ribs never assume 

 quite the importance of the primaries; all the ribs lose definiteness 

 toward the anterior end of the shell. There are no color features. 

 The shell is more regularly tapering and regularly curved than is 

 DentaUum antillarwm. None of the museum specimens show an 

 apical notch. 



Length, 20 mm.; diameter, 2 mm.; arc 1.5 (juvenile), Brazil. 



Length, 23.75 mm.; diameter, 2 mm.; arc L5 (no tip), Tampa. 



Length, 32 mm.; diameter, 5 mm.; arc 2 (no tip), Sanibel Island, 

 Florida. 



This is an example of the Brazil-Gulf of Mexico distribution. It 

 belongs to the littoral zone. Though closely allied to the widely 

 distributed DentaUum antillarum, it must not, on the other hand, be 

 confused with the hexagonal D. (lisparile, of similar geographic range, 

 and which it superficially resembles. 



I am unable to find Doctor Ihering's description of this species, but 

 have based my diagnosis upon a specimen from Ihering himself, 

 probably a topotype from his original lot. As remarked, the species 

 is closely related to D. antillarum in its general appearance, but it 

 lacks the translucent spots and the microscopic transverse intercostal 

 sculpture, in place of which are coarsely raised growth lines. The 

 Florida lots here referred to average a trifle larger than Ihering's 

 specimen, but are certainly conspecific. Both the primary and sec- 

 ondary ribbing of these are coarser and more prominent than in 

 D. antillarum and the strong curve in the tip is lacking. 



The museum records are set forth in the following table : 



Num- 

 ber of 

 speci- 

 mens. 



Cat. No. 

 U.S.N.M. 



Locality. 



Remarks. 



225817 

 53906 

 83783 

 61018 

 53904 

 .53907 

 225015 

 228738 



Brazil 



Marco, Florida 



Charlotte Harbor, Florida 



Tampa Bay, Flori ia 



Cape Romain, Florida (Stearns collection) 



Floriila 



Port Tampa, Florida, U . S. B. F 



Sanibel Island 



(Iherins) author's specimen. 



2 fms. (Hemphill). 



(Dall). 



5 fms. (Simpson). 



(Jewett). 



(Hemphill). 



4 fms. Sand. 



(W. F. Clapp). 



DENTAUUM (ANTALIS) DISPARILE Orbigny. 



Plate 6, figs. 4, 5, 6, 7, 8. 



1846. DentaUum disparile Orbigny, Moll. Cuba, vol. 2, p. 202, pi. 25, figs. 14 17 

 1878 (?). DentaUum disparile, Arango, Contrib. Fauna Cubana, p. 232. 

 1892 (?). DentaUum disparile, Dall, Trans. Wagner Free Inst., vol. 3, p. 440. 

 1897. DentaUum disparile, Pilsbry and Sharp, Tryon's Man. Conch., vol. 17 

 p. 56, in part, pi. 14, fig. 19 (figs. 16, 17, 18, 20, and 21 are probably 

 antillarurn). [1881 Not Dall, Bull. Mus. Comp. Zool., vol. 9, p. 37. J 

 [1889 Not Dall, Bull. Mus. Comp. Zool., vol. 18, p. 424.] 

 The shell is moderately and rather evenly curved, the curvature 

 not being restricted to the apical portion; the tip is hexagonal, long 



