394 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



SOLENOCONCHA. 



Dentalium occidentale Stimp. 



Shells of New England, 1851 (based on Z). dentale Gonlcl, Ist ed., j). 155, fig. 



5, not of European authors). 

 Dentalium dentale Gould, Invert, of Mass., 2d ed., ij. 260. 

 Dentalium abi/ssorum M. Sars, 1858. 

 Dentalium striolatum Jeffreys (wom Stlmjison). 

 Antalis striolata G. O. Sars, Moil. Reg. Arct. Norv.,x5. 101, pi. 7, fig. 1; pi. 20, 



figs. 10 a, I) ; pi. i, figs. 1 a-c, dentition (non Stimpson sp.). 



This species is abundant on muddy bottoms, in 50 to 300 fatlioms, all 

 along the coast of New England and Nova Scotia. 



Mr. Jetfreys, misled by a singular and unaccount>able mistake, has 

 constantly applied to this sulcated species the name given by Stimjison 

 to our common, shallow- water, nearly smooth form. In this mistake G. 

 O. Sars and others have followed him. 



The question as to the specific distinctness of these two forms I do not 

 propose to discuss at this time, but it is equally desirable that the 

 respective names should be correctly aj^plied, whether we regard the 

 forms as varieties or species. Of D. striolatum, I have dredged thou- 

 sands of specimens in shallow water in the Bay of Fundy, in the same 

 region where Stimpson's original specimerfs were taken, and among them 

 no specimens of " D. occidentale " are to be found. In other localities, how- 

 ever, both species occur together. Both were taken this season on the 

 outer banks, off Newport. But I), occidentale was by far tbe most com- 

 mon, and was abundant in the deeper stations, where J), striolatum did 

 not occur at all. 



Among the specimens taken by us there are many that are more 

 strongly ribbed and sulcated than usual, the ribs being more or less 

 angular and elevated. In some of these, which are slender and about 

 an inch long, the internal surface of the shell has grooves corresi)onding 

 to the external ribs, the shell being thin, but of uniform thickness, so that 

 the two surfaces are parallel. In others of the same size the bore of the 

 shell is smooth and round, the shell being thickened opposite the ribs. 

 I ain not prepared, hoAvever, to say that this is anything more than a 

 varietal difference. 



The form of the posterior notch varies in all our species (or varieties) 

 from a shallow notch to a triangular cut, and even to a deei^ slit. 



Siphonodentarum vitreum Sars. 



G. O. Sars, op. cit.,p. 103, pi. 7, figs. 2 a-c; pi. i, figs. 2 a-/ (dentition). — Yer- 

 rill. Trans. Conn. Acad., v, pi. 42, fig. 10. 



A line, large specimen, probably belonging to this species, was 

 dredged by the party on the "Bache", in 1873, in the Gulf of Maine 

 (station 12 B), in GO fathoms, mud. 



The ishell is smooth, round, very thin, transparent, and lustrous. It 

 is slightly curved and expands gradually to the anterior end. The pos- 

 terior opening is smaU and round, without lobes, but it probably has 



