38 ACICULID.E. 



Dr. Gruithuisen describes the operculum as 

 formed of concentric rings: this is very pardon- 

 able, as it is very easy to overlook its spiral cha- 

 racter. 



Earn. 6. ACICULID^S. 



Muzzle annulated, produced. Tentacles subulate, 

 not swollen at the end. Eyes large, on the back 

 of the neck, rather behind, and between the base 

 of the tentacles (fig. 10.). Gills vascular; jaws 

 none. Foot oblong ; divided across in the mid- 

 dle. Male organ large, at the hinder part of 

 the base of the right tentacles, exserted like a 

 third tentacle. Shell spiral, sub-turreted ; aper- 

 ture oblong ; peristome simple ; outer lip rather 

 dilated, sinuous. Operculum horny, spiral, of 

 few rapidly enlarging whorls. Terrestrial, 

 unisexual. 



On account of the shape of the shell, the animals 

 have been placed with Bulimi. 



When the animal was first discovered it was then 

 arranged with Auriculida, on account of the position 

 of the eyes. But M. Ferussac (Diet. Class. H. 

 N. ii. 90.), in 1822, first noticed the operculum; 

 and it has been more lately described by Mr. Alder, 

 the Abbe Dupuy, and others. 



The animal is very rapid and irritable, but comes 

 out of the shell with great hesitation. It carries 

 the shell horizontally when it walks. Preferring 

 dampness, it hides itself from the sun, secreting 



