94 



TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Macrocyclis Duranti, Newcomb. 



Shell widely umbilicated, depressed, discoidal, of a dead white or greenish 

 color, thin, with very coarse, rough stria? ; whorls 4, flattened, the last dis- 

 Fig 13 coidal, not descending at the aperture, below broadly excavated 



and channelled; suture delicate; aperture removed from the 

 axis, transversely rounded ; peristome simple, acute, its termi- 

 nations approaching, joined by callus, that of the columella not 

 reflected. Greater diameter, 4 mill.; height, 1-J- mill. 



Helix Duranti, Newcomb, Proc. Cal. Acad. Nat. Sci., III. 118 



(1864). — Pfeiffek, Mom, V. 171 (1863). 

 Patula Duranti, Tryon, Am. Journ. Conch., II. 263, PL IV. 

 Fig. 53 (1866). 

 Hyalina Duranti, W. G. Binney, L. & Fr.-W. Sh., I. 37, Fig. 49 (1869). 



A Californian Region species, extending also into the Lower California 

 region as far south as the mouth of the San 'Pomas River. I have received it 

 from Santa Barbara Island, Catalina Island (Hemphill), and from near San 

 Francisco. 



Jaw as usual in the genus. Lingual membrane (PI. I. Fig. E) : see pp. 89, 90. 



Spurious Species. 



Macrocyclis Elliotti, Tryon (Am. Journ. Conch., II. 246) is a true species of Zonitcs, 

 characterized by caudal mucus pore, parallel longitudinal furrows above the margin 

 of the foot, and the presence of perfect lateral teeth. 



Zonites, Montf. 



Animal heliciform ; mantle subcentral, protected by an external shell. 

 Respiratory and anal orifice on the right of the mantle under the peristome 

 of the shell. Orifice of generation under the mantle. A distinct locomotive 

 disk to foot. Two parallel well-marked longitudinal furrows above the margin 

 of the foot, meeting at the extremity above a longitudinal caudal mucus pore. 



Shell broadly umbilicated, orbiculate, convex or discoidal, striated or 

 decussated, beneath smooth and shining; whorls 6 or 7, gradually increasing 

 in size; aperture oblique and lunate; peristome straight, acute, and slightly 

 thickened internally. 



Formerly I separated the American species into two genera, Zonitcs and 

 Hyalina, respectively characterized by the presence or absence of a distinct 

 locomotive disk to the foot, and well-marked furrows running Fig 14 

 above and parallel to the edge of the foot, meeting above the 

 extremity of the tail over a distinct caudal mucus pore (Fig. 14). J 

 I now place them all in Zonitcs, as all I have examined (Z. fuli- 



, . , . , . ,.,.,.* Tail of Zonites 



ginosus, capnodes, inornalus, Iczvigatus, acnussus, scuiptilis, ligcrus, surpressus, 

 intcrlcxlus, gularis, supprcssus, cerinoidcus, cellarius, placentida, 



