ANCULOSA. 401 



the middle one widest, and the superior one placed nearest the sut- 

 ure aud revolving on the spire; the middle one is concealed on the 

 spire by the suture; aperture much dilated, ovate, acute above; 

 labium a little flattened ; labrum Avidely and regularly rounded, with- 

 out any protrusion near the base; base slightly angulated, without 

 any sinus or undulations; umbilicus none. 



IlabUat.— Inhabits Falls of the Ohio. 



Length, less than i of an inch. 



Varuty A. Inferior band obsolete. 



Variety B. Bands obsolete. 



Ohservatians. — This species is allied to the preceding (3/. isofjona), 

 but is obviously distinct in its general appearance; the volu- Fig. 797 

 tious are destitute of a shoulder, and the aperture is ovate, ^^ 

 acute above. It is a pretty shell, the bands being very con- ^^ 

 spicuous, strongly contrasting with the yellow general color, partic- 

 ularly in the young and half grown shell. I obtained about a dozen 

 specimens on the rock}- flats of the falls of the Ohio at the lower 

 end of the island which is nearest to Louisville. — Say. 



Melania viridis described by Mr. Lea is the same as Mr. 

 Say's variety B of triUneata and does not exhibit distinctive 

 characters amounting to specific weight. The following is the 

 description : — / 



Melania viridis. — Shell smooth, subfusiform, rather thick, green; 



spire short, obtusely conical; sutures linear; whorls Ave, somewhat 



convex ; aperture ovate, rather large, Avhite. 

 Fig 798. ° 



Habitat. — Vicinity of Cincinnati, Ohio. 



Diameter, -27 ; length, -32 of an inch. 



Observations. — Inhabits with the 31. occidental is, herein 

 described, and resembles it. It is a smaller species, has one more 

 whorl, has a higher spire, and among nine individuals before me I 

 see no indications of transverse stria;. The aperture is rather more 

 than half the length of the shell. — Lea. 



In treating viridis as a s^'nonyme of triUneata I follow the 

 opinions expressed with reference to it by Messrs. Ilalderaan, 

 IJrot, liinney and Anthony. The two former gentlemen to- 

 gether with Dr. Jay, unite in considering costatu.s, Antliony, 

 and occidentalism Lea, as sjnionymes also. In this opinion I 

 cannot coincide ; the two species appear to me to be well sep- 



I-. F. W. 8. IV. 2G 



