ENTALINA. 133 



Dentalium f (Entalina) tetragonum Brocc. MONTEROSATO, Notiz. 

 Conch. Foss M. Pellegr. e Ficarazzi, p. 27 (1872). Siphonentalis 

 tetragona G. O. SARS, Moll. Reg. Arct. Norv., p. 105, pi. 20, f. 13 

 a-c, shell ; and pi. I, f. 4, dentition (1878). Siphodentalium tetra- 

 gonum Brocchi, JEFFREYS, Ann. Mag. N. H. (5), vi, p. 317 (1880). 

 Entalina tetragona Brocc., MONTS., Bull. Soc. Malac. Ital., vi, p. 

 64 (1880). Not Dentalium tetragonum Brocchi. 



" Dentalium dentalis or quadrangulare " MACANDREW, Rep. Brit. 

 Asso. Adv. Sci. for 1850, p. 267 (1851). 



Dentalium abyssorum, juv., M. SARS, Om de i Norge forekom- 

 mende fossile Dyrelevninger fra Qvartserperioden, University Pro- 

 gramme for 1864, p. 43, f. 107-109. 



Siphonodentalium pentagonum M. SARS, Forh. Vidensk.-Selska- 

 bet i Christiania, for 1864, p. 307, pi. 7, f. 45-51 (1865). 



The strongly pentagonal posterior part of the shell, with rather 

 coarse riblets between the angles, and an oblique, circular aperture, 

 readily distinguish this from any Dentalium. 



The soft parts, as figured by M. Sars (see pi. 14, figs. 30, 37, 38) 

 have the characters of Siphonodentalium. The very young have a 

 bulbous, pear-shaped nucleus, as in Dentalium. Jeffreys states that 

 " the terminal notches, usually one on each side, agree with those in 

 most species of Siphodentalium. Some Norwegian specimens have 

 five notches, and are jagged like S. vitreum" The specimens we 

 have seen are either even- edged or irregularly jagged at the apex. 



We have compared specimens of E. platamodes Watson, and 

 consider it sufficiently distinct. 



E. PLATAMODES (Watson). PL 23, figs. 3, 4, 5. 



Shell small, solid, finely tapered, curved, especially toward the 

 apex, five-sided, with four sharp corners, which are nearly right 

 angles, and one very obtuse angle along the concave curve ; these 

 all tend to disappear toward the apex, the young shell being rounded. 

 Sculpture : the angles of the shell project more or less in a sharp 

 rounded rib, which is sometimes double ; there are a few longitudi- 

 nal striae, regular, O'Ol inch apart, strongest near the angles, more 

 or less obsolete as they recede from these. Neither end is fresh 

 enough for description. Length 0*47 inch, breadth 0'049 inch. 

 ( Watson). 



North of Culebra Island, West Indies, lat. 18 38 f 30" N. t long. 

 65 5' 30" w., 390 fms. (Challenger) ; Florida Strait, 8S\ miles S. of 



