ASIPHONIBRAlSrCHIATA. VO 



testaceous part of the Ocytlioe, and that the broad membranes 

 which in some representations have been artificially placed as 

 sails, are naturally bent backwards over the shell Hke the mantle 

 of some other molluscs. The interesting experiments of Ma- 

 dame Power, in the Mediterranean, have contributed very 

 materially to lead the investigations of naturalists to a satisfac- 

 tory conclusion. This lady kept a cage under water, in which 

 Argonautse were bred in great numbers, giving her an opportu- 

 nity of tracing the gradual development of the shell in all its 

 stages, from the elastic and transparent nucleus to the fuU 

 grown " Paper Sailor." PL xxui. fig. 485. 

 AEGTJS. Poli, 1795. Equivalve pectens, like P. opercularis. 

 AEIANTA. Leach, 1819. A sub-genus of land shells, containing 



Helix arbustorum, Auct. (G-ray, Turton, p. 137.) 

 AE-IOlSr. Eerrussac, 1817. A genus of slugs, originally described 

 as having no sheEs, but the shell of which is now ascertained to 

 be a LimareUa. 

 AEEOW-HEADS. One of the names by which fossils of the 



genus Belennites were formerly known. 

 AETEMIS, or AETHEMIS. Poli: Dosikia? ScopoH. A genus 

 of bivalve shells, distinguished from those of the genus Cythe- 

 rsea by having a rounded, denticular form, and a deep, angular 

 sinus in the palleal impression ; although palleal impressions of 

 the Veneres are subject to great variations, this may be consi- 

 dered a pretty well defined genus. The author is preparing a 

 Monograph in the Thesaurus Conchyliorum, containing 60 

 species. A. lincta, PI. vi. fig. 118. 

 AETICULATED. (Jointed.) Applied to distinct parts of shells, 

 which are fitted or jointed into each other, as the valves of 

 Chitones and those of Balani. The operculum of Nerita is said 

 to be articulated to the columella, having a small process by 

 which it is as it were locked under the edge. See Introduction. 

 The word is also applied to the Cirri, which protrude from the 

 oral openings of Cirripides. 

 AETICULINA. D'Orb. A genus of microscopic Foraminifera. 

 ASIPHONIBEANCHIATA. Bl. The second order of Paracepha- 



