70 APLYSIA. 



so called because it forms a kind of axis on which the volutions 

 turn. The outer lip, sometimes called the labrum, is on the 

 opposite side, or the farthest from the axis. If the edges of the 

 inner and outer lips unite all round, they are described as com- 

 posing theperitreme. In fig. 318, the aperture is marked by the 

 letter a. 



APHRQDITA. Lea. (from A^poSirr/, Greek name of Venus.) 

 A genus composed of Cardium Groenlandicum, Auct. fig. 123*. 

 and other similar species of Cardium, the teeth of which are 

 either wholly wanting, or very indistinct. Northern Ocean. 



APICIAL. Belonging to the apex. The apicial extremity of the 

 aperture of a univalve shell, is that which is nearest to the apex 

 of the spire. 



APICULUM. Humph. Trochus, Lam. 



APLEUROTIS. Rafinesque. A genus unfigured and imperfectly 

 described as differing in some respects from Terebratula and other 

 Brachiopodse. 



APLEXUS. Fleming. A genus composed of Physa Hypnorum, 

 Drap. &c. and described as having the inner lip simple, and not 

 spread over the body whorl. 



APLODON. Rafinesque. A genus proposed to be established at 

 the expense of the genus Helix, but upon what grounds does 

 not appear from the imperfect description which is unaccompanied 

 by a figure. 



APLUSTRE. Schum. A genus formed for the reception of those 

 species of Bulla which have the spire uncovered. Ex. Bulla 

 Aplustre, (aplustre, a flag.) Auct. fig. 289. 



APLYSIA. Linn, (a, without; \~l\vw, to wash.) Fam. Laplysiens, 

 Lam. Aplysiana, Bl. — Descr. Horny, transparent, clypeiform, or 

 shield- shaped, placed horizontally on the back of the animal, with 

 its convex side uppermost ; apex slightly incurved. — Obs. The 

 animal producing this shell has derived its name from the purplish 

 liquor which it exudes, when disturbed. In contour, it has been 

 fancied to present a certain likeness to a hare crouching, and on 

 this account was called Lepus marinus, or sea hare, by the ancients. 

 The shell bears a strong resemblance to Dolabeila, which, however, 



