40 



thirteen years ago, which at the time indeed immediately suggested 

 the formation of the genus Parthenia, but which the progress of 

 Conchology, in the more recent establishment of Eulima, seems to 

 have rendered really interesting. 



The genus Turbonilla (rectius Turhinella) of Risso, though perhaps 

 composed in chief of true Parthenice, is not so constituted, even 

 should this supposition prove correct, as to supersede or clash with 

 the reception of Parthenia. Its definition is extremely incomplete 

 and faulty, and it differs no less in its limits than its constitution ; 

 whilst its very author places in his Eulima and in Turritella some 

 undoubted species of Parthenia. The name, moreover, rightly 

 spelled, is long preoccupied by a well-known genus of Lamarck. 



The group, however, constituted as above, appears sufficiently di- 

 stinct from every other. From Melania it is distinguished primarily 

 by being marine instead of fluviatile, and in the shell being destitute 

 of a dark-coloured epidermis. It differs from Rissoa or Cingitla, 

 Flem., in the animal, much as LimtKea does from Physa, and in the 

 shell, as Turritella does from Littorina; whilst from Eulitna, Sow., 

 the shells are at once distinguished by their rough or sculptured, 

 ribbed, and generally cancellated surface ; and the animal wants the 

 lateral membranes and subulate tentacula of Turritella, from which 

 the shells also differ in the transverse ribs or plaits of the volutions, 

 and in the shape of the aperture and of the opercle, the nucleus of 

 which is also probably eccentric and anterior ; but this, without de- 

 struction of the specimens, I cannot ascertain. 



The name is formed from TrapOevos, a virgin ; the word irapdej'ia, 

 virginity, expressing well, in contrast with Melania, the simple ele- 

 gance and purity so remarkably characteristic of these shells, which 

 are whoUy colourless, and of a spotless milk or ivory whiteness. 



Several recent species of this group are found in the Mediterra- 

 nean, and two at least in the British seas. Others appear also to 

 occur subfossil, in the tertiary beds of Sicily and Nice. 



The animal of the shell, called by Montagu Turbo unidentatvs 

 (Odosto7nia of Fleming), would appear, from the observations of my 

 friend, the Rev. M. J. Berkeley, to be very similar. But the shell, 

 in most points, differs, except in having a fold or plait upon the co- 

 lumella. Still future observations may warrant possibly the modi- 

 fication of the characters of Parthenia, for the reception of this shell 

 and its allies. 



Species quaedam. 



1. Parthenia BULiNEA. P . testa subcylindraceo-attenuata, oblon- 

 giuscula, juniore ovato-tereti : dnfractibus planis, elegantissime 

 reticulato-cancellatis, striis spiralibus crebris (equidistantibus, 

 iransversas cequidistantes decussantibus ; sutura distincta impressa: 

 columella postice torta, uniplicata. 



a. subventricosa. 



Lat. li — If Long, apertae.' U ,. , 3 .... 



T-— r — -^~i — ' hn. : f 7 — : = -r h"- vel -z-- millim. 



Long. 5 Long, testee 5 10 



