90 



expanded at maturity into a lobe ; in one of the three only recent species 

 known, A. occidentalis, from the northern shores of Western America, the 

 lobe is simple, in the remaining two A.pes-Telicam, and pes- CarLon is of 

 the Mediterranean, it is digitated, the shell being of a corresponding 

 structure. ,^.„....„.^.„..,._„.. ..^ 



Species. 



1. occidentalis, Beck. 2. pes-Carbonis, Brong. 3. pcs-Pelicaiii(i2o.s^.)Lain. 



Genus 4. ROSTELLARIA, Lamarck. 



Animal ; elongated, disc divided into two parts, the posterior 

 cylindrical, ohliqiieh) truncated, and carrying a horny iinguiform 

 operculum upon the truncature, the anterior Jtattened arid 

 rounded, serving the animal to attach itself to solid bodies ; 

 head large and thick, prolonged into a proboscis-shaped mu::zle, 

 slit in front ; tentacles diverging, cylindrical, two forked, the 

 inner branch being slim and pointed, the outer truncated at the 

 sicmmit,- with the eye situated upon the truncature. 



Shell ; fusiform, j^rolonged at the base iiito a canal which is some- 

 times very long and slender ; whorls slightly convex, sometimes 

 furnished here and there with a varix ; lip toothed, or digitated. 



It appears from Ehrenberg's characters of the animal above noticed, tliat 

 the liostellar'ue whose graceful fusiform shells are so much admired by the 

 collector, and are the pride of liis cabinet, have a much closer affinity with 

 the Pterocerce and StromJjt, than with the Aporrhaides which have been 

 liitherto associated with them, or the Fusi, to which they were approximated 

 by Ferussac and De Blainville. The disc presents the same peculiar modi- 

 fication of structure as in Pterocera and Strombus ; divided into two parts, 

 the animal is said to acquire motion by executing a succession of leaps, 

 instead of the ordinary mode of progressing by dilatation and contraction. 



The Rostellaria may be easily recognized by the elegant fusiform growth 

 of the shell, with its pecidiarly dentated, or finely digitated Hp ; they are 

 very limited in species, and are principally from China and the Moluccas. 



Species. 



1. curta, Sow. 3. fissa, Desh. 5, Powisii, Petit. 



2. curvirostruni, Lam. 4. fusus {Stromh.), Linn. 



