PTEROPODA. 



LiMACINA. Fig. 3. 



Testa tenuis, fragilis, spiralis, discoidea, lateribus umbili- 

 catis, dorso et subttis carinata, caring membranacea^ 

 lamellari. 



We bave been favoured with this very curious little shell 

 from Messina, by the Rev. Robert AVilson. It has exter- 

 nally much the appearance of a very diminutive umbilicated 

 Nautilus. It differs from the other Pteropoda principally 

 in being convoluted; and it may be described as a thin, 

 fragile, spiral, discoid shell, umbilicated on both sides, 

 and carinated on the back and below, with a membrana- 

 ceous lamellar keel. 



Creseis. Fig. 4. 



Testa inverse pyramidalis, hyalina, tenuissima, fragillima, 

 subtus acuminata, superne aperta, parte dorsali lon- 

 giore; linea dorsali semitortd ex vertice ad basin de- 

 currente. 



Shell inversely pyramidal, transparent, very thin and 

 brittle, pointed at the lower end, wider and open at the 

 upper, dorsal part more lengthened and pointed, with a 

 partly twisted line running from the vertex to the base. 

 Found in the Mediterranean. 



VaG INULA. Fig. 5. 



Testa inverse pyramidalis, tenuis, fragillima, medio ven- 

 tricosiusculo; infra acuminata, aperturd minimd; 

 superne lateribus £equalibus, apertura magna, ob- 

 longd. 



Shell of an inversely pyramidal form, thin, very brittle, 

 rather ventricose in the middle, acuminated and having a 

 very small aperture at the lower extremity ; upper end 

 with both sides equal, and a large oblong aperture. 



Only known in a fossil state, in tertiary beds near 

 Bordeaux. 



