72 AECA. ■ 



testaceous. The species are found in the Mediterranean, 

 European, and West Indian Seas. A. Petersoni. PL xiii. fig. 

 254. 



APLYSIACEA. Bl. The second family of the order Monopleu- 

 robranchiata, Bl. The animals composing this family are either 

 destitute of shells, or are provided with iuternal ones, which are 



. flat, open, oblique, with the apex or nucleus slightly incurved, 

 not distinctly spiral. This family contains the genera Aplysia 

 and Dolabella. The first sub-spiral, with the apex terminal ; 

 shell thin, horny, Eig. 254. The second the same, but thick 

 and shelly. Pig. 255. 



APOLLON. Montf. Eanella. Lamarck. 



APOEOBEANCHIATA. Bl. The first order of the second 

 section of Paracephalophora Monoica, Bl. The Thecosmata is 

 the only family of this order containing any approach to shells, 

 these are Hyalsea and CymbuUa. 



APOEEHAIS. Da Costa, 1778. A genus formed of Eostel- 

 LAEiA Pespelicani, Auct. and similar species. Although the shell 

 presents no characters to distinguish it generically from Eostel- 

 laria, those who have examined the soft parts are conviaced that 

 it is distinct. Of the three species now known and figured in 

 part I. of Thesaurus Conchyliorum, by the Author, one is com- 

 mon on our own coast, and in the Mediterranean. See 

 EosTELLABiA ; and our plates : PL xviii. fig. 404. 



AQUATIC. A term applied by some authors to those species of 

 Molluscous animals, which inhabit fresh water, either in rivers 

 or salt water standing pools, as distinguished from the marine 

 or Mollusca. See Presh-water. 



AQUILLTJS. Montf. Triton Lampas, Cutaceus, &c. Auct. 

 Placed by De Blainville in the division of the genus Triton, 

 which is described as having a short spire, being covered with 

 tubercles and umbilicated. Triton Cutaceus. PI. xviii. fig. 309. 



AECA. Linn. (Anglice; a boat.) Fam. Arcacea, Lam. — Descr. 

 Obliquely transverse, subquadrate, equivalve, or nearly so, 

 inequilateral, thick, ventricose, longitudinally ribbed, dentated 



