RAST AMERlCAiSI^ SCAPHOPOD MOLLUSKS. 



61 



DENTALIUM (FISSIDENTAHUM) MERIDIONALE MERIDIONALE Pilsbry and Sharp. 



Plate 9, fig. 2. 



1881. Dentalium Cfms, Dall, Bull. Mus. Comp. Zool., vol. 9, p. 37 (not D. ceras 



Watson). 

 1889. Dentalium ceras, Dall, Bull. Mus. Comp. Zool., vol. 18, p. 425 (not D. ceras 



Watson) . 

 1889. Dentalium cfras, Dall, Proc. U. S. Nat. Mus., vol. 12, p. 294 (not D. ceras 



Watson). 

 1897. Dentalium ( Fissidentalium) candidum meridionalc Pilsbry and Sharp, 



Tryon's Man. Conch., vol. 17, p. 73, pi. 15, figs. 32, 33, 34. 



The shell is very long, large, solid, and strong, moderately curved, 

 regularly and rather rapidly increasing in diameter and somewhat 

 compressed dorso-ventrally, giving a rounded oval section ; an ashen 

 gray or mouse colored periostricum covers a white but not shining 

 surface beneath. The nacreous layer within the shell is bluish white. 

 There are about 16 riblets in the extreme posterior end, separated 

 by wider, shallow^ smoothish spaces between. These primary rib- 

 lets increase to 90 or more flat-topped, gradually broadening riblets, 

 which eventually reduce the intercostal spaces to mere lines and per- 

 sist with but little effacement to the anterior end of adult specimens. 

 No transverse sculpture beyond fine growth lines is present. The 

 apical features consist of a deep notch placed on the convex side. 



Length, 101 mm.; greater diameter, 12.8 mm.; lesser diameter, 

 12.3 mm.; arc, 5; type. 



Length, 108 mm.; greater diameter, 14 mm.; lesser diameter, 

 13 mm.; arc, 5; Rio de Janeiro. 



The type. Cat. No. 87557 (a), U.S.N.M., w^as dredged by the 

 Albatross at U. S. B. F. Station 2763, 240 miles south by east from 

 Rio de Janeiro, in 671 fathoms, gray ooze, bottom temperature 

 37.9° F. 



This deep-water subspecies is by far the largest of anj^ of the 

 Dentalia so far known from the w^estern Atlantic. The mouse or 

 ashen colored outer shell layer is uniciue among all species of the area. 

 This subspecies is restricted to the very large, broad forms from off 

 Rio de Janeiro. A worn fragment from Barbaldos, taken in 100 

 fathoms. State University of Iowa Expedition, is clearly referable 

 to this subspecies. 



The f ollowintr are the museum collection records : 



Num- 

 ber of 

 speci- 

 mens. 



Cat. No. 



U.S.N.M, 



Locality. 



87557 



3144.52 

 87557 

 87538 

 95353 



Southeast of Rio de Janeiro, U. S. B. F. Station 

 27C.3. 



Brazil, U. S. B. F. Station 2763 



Rio de .laneiro, U. S. B. F. Station 2763 



do 



North of Yucatan Bank, Blake Station 33 



671 fms., 37.9", br. glob. oz. 



Do. ■ 

 Po. 



1)0. 



1,568 fms. 



' Type. 



