174 TANTHINID^. 



low water among Gigartina mammillosa and Corallina 

 officinalis on the Plateau du Fonr in Lower Brittany, 

 and in M. Martinis collection at Martigues other speci- 

 mens similar to the last from Cape Couronne in the 

 Gulf of Lyons; and I took this species myself at 

 Spezzia. 



It is the most slender of all the Odostomice. My 

 largest specimen (Zetlandic), which is a line and a 

 quarter in length, has a diameter in the widest part 

 equal to one-fifth only of that dimension. 



Family XVIL lANTHrNID.^, Deshayes. 



Recluzia is the only genus besides layithina that has 

 any good claim to be a member of this select and pecu- 

 liar group ; and as the systematic position of the former 

 genus is somewhat doubtful^ I will content myself with 

 giving the characters of lanthina only. 



De Blainville called the family Oxystoma, Brown lan- 

 thinea, and Agassiz lanthinoidcB . 



Genus lAN'THINA^ Bolten. PL III. f. 1. 



Body globular, with a short posterior convolution : mantle 

 folded at the base of the shell, and exjianding- into two irregular 

 flaps or lobes, that probably serve as imperfect natatory organs 

 (" epipodial fins," Morch), and are fringed with fine cilia : head 

 consisting of a thick, cj^lindrical, and occasionally swollen muz- 

 zle, terminating in a cloven mouth, which is encircled with 

 minute and flexible cilia ; and it is provided with a pair of carti- 

 laginous jaws and a spinous tongue ; this latter organ is armed 

 with very long and awl-shaped uncini or lateral teeth, arranged 

 in two rows, but it has no rhachis or central tooth : tentacles 

 conical, each furnished at its base with a short finger-shaped 



* From its violet colour. 



! 



