250 Mr. J. Gwyn Jeffreys on Di^edging 



proposed for the reception of a small Sicilian fossil — his Denfa- 

 liwn ovulum) the shell is not cylinch'o-conical as in Siphono- 

 dentalium, but is tumid in the middle or anterior portion, some- 

 times awl-shaped; and the mouth is encircled by a narrow rim. 

 In Cadulus the shell is quite smooth, transparent, and lustrous; 

 in Siphonodentalium it is striated or exhibits the lines of growth, 

 and is semitransparent. The long-lost Dentalium gadus of 

 Montagu, an allied species {D. clavatwn of Gould) from the 

 China Sea, another species which I observed in the late Mr. 

 Cuming's collection, from Mindanao (erroneously named D. 

 acuminatum, Deshayes), and D. coarctatum of Lamarck (a ter- 

 tiary fossil) apparently belong to Cadulus, and certainly not to 

 Ditrupa (properly Ditrypa) — a genus of testaceous Annelids the 

 shell of which is different in structure and composition from 

 that of Cadulus or of Siphonodentalium (the mouth is contracted 

 or pinched-in), and the animal is .annulose and has a circular 

 operculum. On the other hand, several kinds of shelly cases 

 described as Dentalia really belong to Ditnjpa. If Cadulus is not 

 generically distinct from Siphonodentalium, the former of these 

 names has priority ; and we shall thus be able to expunge a more 

 than sesquipedalian name from the terminology of the Mollusca. 

 The diagram now exhibited is an enlarged representation of the 

 figures of S. Lofotense and S. subfusiformis, in an admirable 

 paper by Professor Sars, published in the Transactions of the 

 Academy of Sciences at Christiania for 1864; and it will serve 

 to explain the nature of these extraordinary moUusks. One of 

 our species is 



Siphonodentalium Lofotense, Sars 

 (" Malacozoologischc Jagttagelser," in Vid.-Selsk. Forh. 1864, 

 p. 17, figs. 29-33), ranging from the Loffoden Isles to Chris- 

 tianiafiord, at depths of between 30 and 120 fathoms. It was 

 rather plentiful among sandy mud in St. Magnus Bay, at the 

 depth of from 60 to 80 fathoms; and I had found it in 1846 

 when dredging off Skye, in 1864 off Unst, and last year in the 

 Minch. The shell may easily be passed over (as it was by 

 me) for the young of Dentalium entalis ; but it is more curved 

 and cylindrical, the mouth and corresponding lines of growth 

 slope backwards, and the margin of the posterior orifice is regu- 

 larly jagged (having two slight notches on each side), and this 

 extremity does not form a bulbous point in the fry. One of 

 the characters given by Sars (" margine apertures posterioris 

 integro '') should be amended. My observation of the animal 

 agreed with his, except that the foot is vermiform and has a 

 fine point, the disk being expanded and assuming the shape of 

 a flower only when the Siphonodentalium wishes to obtain a 

 fulcrum and keep its place in the sand. The foot of Nucula 



