48 DENTALIUM-ANTALIS. 



p. 5) and G. O. Sars (Moll. Reg. Arct. Norv., p. 101). It is, in our 

 opinion, specifically different from striolatum Stimp., but seems to be 

 identical with the later D. abyssorum M. Sars. D. attenuatum Say 

 is a somewhat similar Miocene species, differing in the characters 

 of the apex. The description and synonymy of Z>. abyssorum here 

 follows. 



D. abyssorum M. Sars. (PL 8, fig. 21 ; pi. 9, fig. 40). Longer 

 and more slender than D. entails; lightly arcuate toward the apex ; 

 less solid. White or ashen, little shining, longitudinally striolate, 

 about 20 (16-24) more distinct striae at the middle, rarely extending 

 to the aperture, and sometimes quite raised, sometimes less distinct 

 and almost obsolete. Apical fissure moderately deep ; sheath or 

 tube around the anal orifice short. Length 50, diam. of aperture 4|, 

 of apex 1 mill. 



D. abyssorum M. SARS, Christ. Vid. Selsk. Forh., 1858, p. 52 ; Om 

 de i Norge Forekommende Fossile Dyrelevninger fra Quartser- 

 perioden (University Programme for 1864), p. 42, pi. 3, f. 100-106 

 (1865), exclusive of the so-called young. SEARLES WOOD, Crag 

 Moll. Suppl. i, Pal. Soc. Mem., p. 93 (1871) ; see ibid., i, p. 189, pi. 20, 

 f. 2. D. striolatum Stimp., JEFFR., P. Z. S., 1882, p. 659 ; Ann. Mag. 

 N. H. (5), x, p. 30. D. bremfissum BRUGNONE, Misc. Malac., ii, p. 

 20, fig. 30 (1876). ?Z>. cinerascens ANTON, Verzeich. Conchyl. 

 Samml. Anton, p. 25 (1839). D. entails var. striolatum WATSON, 

 Chall. Rep., p. 5 (1885). Antalls strlolata G. O. SARS, Moll. Reg. 

 Arct. Norv., p. 101, pi. 7, f. 1 ; pi. 20, f. lOa, b, c ; Also folded pi. 

 1, f. 1 (radula). Not D. striolatum Stimpson ! D. tarentlnum ASB- 

 JORNSEN, Nyt Mag. f. Naturv., 1853, vii, p. 350. MALM, Goteborgs 

 Vetensk. o Vitterh. Samhalles Handl., viii, 1863, p. 2, f. 3. Not D. 

 tarentlnum Lam. 



Var. SULCATUM Verrill. 



Shell of moderate size, thin, translucent white, tinged with very 

 pale yellowish or bluish, moderately curved, more decidedly behind 

 the middle, tapering regularly and rather rapidly from the anterior 

 to the very slender posterior end. The entire surface is covered by 

 well marked, nearly regular, narrow raised ribs with nearly perpen- 

 dicular sides and rounded summits, separated by well-defined, 

 strongly marked, concave grooves which are about twice the width 

 of the ribs anteriorly, but posteriorly are of about the same width. 

 The ribs and furrows show on the interior of the shell within the 



