ANCILLARIA. 



Ancilla, Lam., Syst. 1801. Sowerby, Genera of Shells, No. III. 



Ebuhna, Lam., Hist. Nat. des Anim. sans vert. VII. p. 280. 



Ancillaria, ejusd. p. 412. Swainson in Journal of Science, fyc. XVIII. p. 272. 



Testa polita, oblongo-ovata vel oblonga, plerumque subeylindrica; spird plerumque brevi, rum- 

 numquam elongatd, ad suturas oblitd. Apertura longitudinalis, basi effusd. nonnunquam 

 emarginatd; varice calloso, plerumque striato, ad basin columellfp. 



Shell smooth, shining, oblong-ovate or oblong, generally subcylindrical; spire generally 

 short, sometimes of equal length with the aperture; the sutures covered over with a coat of 

 enamel; aperture longitudinal, base effuse, sometimes more or less emarginated; a more or 

 less thickened or callous varix, which is generally striated, sometimes quite smooth, at the base 

 of the columella. 



We do not hesitate to adopt as an improvement the union effected by Swainson* of La- 

 marck's Eburna glabrata and its congeners to Ancilla, or Ancillaria; and we adopt also the 

 latter name in order to avoid unnecessary controversy. The number of recent species described b\ 

 Lamarck is only four under the name Ancillaria and one under that of Eburna; to these Swainson 

 added ten others, one of which, as he suspected, proves to be only a variety ; we now present 

 descriptions and figures of twenty species, so that we have added six species to the number 

 already described :t he varieties, of which we have given graphic illustrations, amount to eleven. + 

 The plan of the following Clavis analytica is adopted from Hooker's Muscologia Britannica ; it 

 facilitates a reference to any species which may occur and of which it may be desirable to 

 ascertain the appellation. In order to ascertain the name of a species by this little table, it is 

 necessary in the first place to refer to the first pair of characters presented in it, if the shell be 

 imperforate, it will be referred to the second pair of characters; if it have no tooth on the lower 

 edge of the outer lip it will be referred to No. 3; next, if the spire be very short, to No. 4; then if 

 the upper edge of the volutions be angular, it is A. Mauritiana; on the other hand if the upper 

 edge of the volutions be rounded, it is A. aperta. By this process any species that is here 

 described will be ascertained with facility. It will, however, be needful to examine afterwards 

 the particular description of the species to ascertain if it agree in all its characters, and save 

 much trouble in referring to the full descriptions of a number of species. 



* However readily we adopt this improvement, we cannot at all coincide with Swainson either in his arguments or conclusions with 

 respect to the other species which have been united to the E. glabrata under the generic name Eburna. This is, however, a subject upon 

 which wecar.mt here enter, though we shall be obliged to revert to it hereafter in another place. 



f The plan which we have adopted for this extensive publication, viz. a series of monographs, will enable us without inconveuienee to 

 add at any future time an appendix to each monograph; we therefore earnestly request the possessors of species not here represented to 

 communicate them to us, in order that when there shall be a sufficient number we may publish them in an appendix. 



