ZONITES. 



293 



Chemnitz, ed. 2, II, 201, tab. ci, f. 5-8.— W. G. Binnev, Terr. Moll. 



IV, 122.— Mks. Gray, Fig. Moll. An. pi. cxci, f. 4, ex Best. Journ. 



— H. & A. Adams {Gastrodonta), Gen. Rec. Moll. pi. ixxi, f. 4 (no 



descr.). — Reeve, Con. Icon. no. 719 (1852). 

 Helix bicostata, Pfeiffek, Mou. Hel. Viv. I, 182 ; Symbolce, III, 097 



(1852); in Chemnitz, ed. 2, II, 19(3, pi. c, f. 21-23 (1846),— 



Reeve, L c. 

 Gastrodonta gularis, Tbyon, Am. Journ, Concla. II, 257, pi. iv, f. 39 (1866). 



It is found from Pennsylvania and Ohio to the Gulf of Mexico. 

 Also in the postpleiocene of the Mississippi Valley, 

 There is a variety with an open umbilicus. 

 Lingual membrane with 88 rows of (38 — 1 — 38) teeth each ; 



Fig. 526. 



^MmiBBQ® 



LiuguaJ deatitioa of Zonites gularis. 



centrals with one long central and two short lateral cusps ; 

 laterals bicuspid ; uncini thorn-shaped. 

 Tail with a mucus pore. 



Zonites snpprcssa, Sat. — Shell convex depressed, thin, pellucid : 

 epidermis polisherl, yellowish horn-color ; spire flat ; whirls six, witli 

 crowded, minute, oblique strise ; suture impressed, distinct ; aperture 

 transverse, not expanded ; peristome simple, thin at 

 its edge, thickened within ; base rather convex, near pjg^ 527. 



the aperture opaque, yellowish-white ; umbilicus 

 email, but rounded and distinct, in young shells, 

 obsolete or hardly apparent in older ones ; within 

 the peristome are one or two lamelliform, elongated, ZonUe^ suppressa. 

 oblique teeth. Greater diam. 5, lesser 4 ; height 2 

 mill. 



