of the Genus Ancillaria. 273 



longs to Oliva, and its modifications will be found very essential in 

 the discrimination of species; the relative length of the spire 

 will also afford a useful auxiliary character, although it is compa- 

 parative, and, in some instances, variable. M. Lamarck, on the 

 contrary, has attempted to draw specific distinctions from the 

 striated base of the columella, but this, as being common to nearly 

 allthe species, becomes generic. It is, probably, to this cause, and 

 the bad figures that have been given for the species, that we must 

 attribute the mistakes of those who have written upon the subject. 

 With these preliminary observations, I shall proceed to detail 

 the characters of the genus, and its affinity to others; oflferingsuch 

 further remarks as appear necessary, under the respective species 

 to which they more immediately belong. 



ANCILLARIA. 



Ancilla vel Ancillaria^Eburna — Lamarck. 

 Ancillus — De Montfort. Ancilla — Sowerby. 

 Testa oblonga, sub-cylindrica, nitida. Spira plerwniqiie brevis ad siituras 

 non canaliculata. Aperlura lonff'dudinalis, basl vix emarffinal.S, 

 efusd. VarM! callosus et oblique atrialus ad basin columellte posilus. 

 Epidermide caret. 

 Shell oblong, sub-cylindrical, polished. Spire in general short, the suture 

 not channelled. Aperture longitudinal, base slightly emarginate. 

 Base of'the columella with a thickened, oblique, striated varix. Epi- 

 dermis none. 



SECTIONS. 

 I. Shell imperforate, varix distinctly striated. 

 ' •■ * Spire short. 



** Spire produced. 

 II. Shell umbilicatcd ; varix obsoletely striated. 



It appears that M. Lamarck first gave this genus the name of 

 Ancilla, which he subsequently changed \.o Ancillaria ; this perhaps 

 was unnecessary, yet as this last name is used in all his later 

 and more popular works, I can sec no advantage in not adopting it. 

 'Y\\G Ancillarice arc marine ; and although the recent species appear 

 confined to the tropical latitudes of the Indian Ocean, several 



