EAST AMERICAN SCAPHOPOD MOLLUSKS. 77 



from the same expedition, at thieir station 116, in 200 fathoms, off 

 English Harbor, Antigua. 



DBNTALIUM (LAEVIDENTALIUM) LIODON ALLOSCHISMUM Pllsbry and Sharp. 



Plate 13, figs. 1, 4, 5, 6. 



1897. Dentaliiim (Laevidentalium) liodon "variety?" alloschismum Pilsbry and 

 Sharp, Tryon's Man. of Conch., vol. 17, p. 108, pi. 21, figs. 40, 41, 42. 



The shell differs from Dentalium liodon liodon only in the position 

 of the apical notch, which here may be on the concave side or more 

 or less laterally placed, and also by its circular section. Doctors 

 Pilsbry and Sharp questioned the value of the subspecies. A larger 

 series of specimens for study would likely disprove the need of any 

 subspecies under D. liodon. 



The type, which is in the collection of the Philadelphia Academy 

 of Sciences, is from St. Martin, in the West Indies, and measures — 

 length, 24.5 nun.; diameter, 1.9 mm. Another specimen is — length, 

 27.5 mm.; diameter, 2.2 mm. 



There are no examples in the National Museum collection. 



Subgenus EPISIPHON Pilsbry and Sharp, 1897. 

 1897. Episiphon Pil.sbry and Sharp, Tryon's Man. of Conch., vol. 17, p. 177. 



Shells are very small, slender, and rather straight, needle-shaped, 

 slightly tapering, thin and fragile, glossy and smooth, and without 

 longitudinal sculpture. The apex has a projecting "pipe" or is a 

 simple orifice with no slit or rarely a notch. 



This subgenus was created to include a group of very small needle- 

 like Dentalia, wholly lacking in any longitudinal sculpture, and pos- 

 sessing to a marked degree a projecting thin tube from the posterior 

 orifice, after the tip is destroyed or lost. This last feature is likely 

 not a biologic one and is by no means confined to this particular sub- 

 genus, but it does seem to be a very striking characteristic of the 

 only species of the subgenus occurring in the western Atlantic. Only 

 one species, Dentalium sowerbyi, with its two subspecies, D. s. sowerbyi 

 and D. s. pelliceri, occur within the faunal areas under consideration. 



KEY TO THE SUBSPECIES OF THE SUBGENUS EPISIPHON. 



Surface coarser, less transparent, American D. s. sowerbyi, page 79. 



Surface smoother, more transparent, Cuban D. s. pelliceri, page 80. 



DENTALroM (EPISIPHON) SOWERBYI Guilding. 



1834. Dentalium sowerbyi Guilding, Trans. Linn. Soc. London, vol. 17, p. 35, 



pi. 3, fig. 7. 

 (?)1860. Dentalium filuvi Sowerby, Thesaurus Couch., vol. 3, p. 89, pi. 22o, 



fig. 4.5. 

 (?)1860. Dentalium fistula Sowerby, Thesaurus Conch., vol. 3, p. 99, pi. 225, 



fig. 62. 



