4 ACT/EONIDyE. 



Shell involute, with the columella plicate or spirally 

 twisted. 



The armature of the lingual membrane, and the form 

 of the head in this family indicate a close affinity with 

 the Bullidce. The animal does not invest the shell, and 

 when observed crawling, the tentacular lobes of the head- 

 disk are reflexed upon the fore part of the body-whorl. 

 The systematic position of this family has been a matter 

 of doubt among Zoologists, some having placed it near 

 the Pyramidellidce, and others with the Auriculid<e. The 

 genera Itieria of Matheron, Actceonella of D'Orbigny, 

 and Cylindrites of Lycett, are fossil, while the extinct 

 fossil genera Cinulia, Gray, Tylostoma, Sharpe, and 

 Ghbiconclia, D'Orbigny, would appear rather to belong- 

 to the Pectinibranchiate family Doliidte. 



Genus ACTyEON, Montfort. 



Shell thin, ovate, transversely striated ; spire produced, 

 acute ; aperture elongated, narrow, anteriorly rounded 

 and entire ; inner lip thin ; columella with a single, 

 oblique plait. 



Syn. Auris Mustelse, Humph. Tornatella, Lam. 

 Speo, Risso. Kanilla, Silvertrop. Myosota, Gray. 



Ex. A. tornatilis, Linncpus, pi. 56, fig. 1. Shell, A. 

 tornatilis, fig. 1, a. 



The broad tentacular lobes are reflexed and partly 

 cover the shell when the animal is observed crawling, 

 showing a very strong affinity with the BullidcB ; the 

 shells, moreover, greatly resemble those of Bullina of 

 Ferussac. From Buccinulus or Solidula, the shell differs 

 in being of a lighter texture, and in the columella being 



