ZONITES. 



123 



Surface of 

 Z. exiguus. 



Fig. 41 shows the peculiar sculpturing of this species. Fig. 41. 



Jaw very low, wide, but slightly arcuate : no median promi- 

 nence to the cutting margin. 



The linofual membrane has 69 rows of 16 — 1 — 16 teeth each ; 

 centrals with one long, slender, middle, and two short side 

 cusps ; laterals 4, of same shape, but bicuspid ; marginals 

 aculeate, diminishing greatly in size as they pass off laterally. 

 The transition teeth and several of the adjoining marginals 

 are described by Morse with a small side spur to their cusps, 

 apparently of the same type as I have figured for Macrocijclis Vancouverensis 

 (PI. I. Fig. B). On PI. III. Fig. D, I give a drawing of a specimen ex- 

 amined by me. I found 16 — 1 — 16 teeth, with 5 laterals. 



Zonites chersinellus, Dall. 



Shell narrowly umbilicated, depressed, transparent, lightest horn-color, shin- 

 ing, with distant incremental wrinkles; spire slightly elevated; whorls 4, 

 scarcely convex, the last depressed-globose; umbilicus narrow, 

 pervious ; aperture oblique, Innately subcircular ; peristome sim- 

 ple, acute. Greater diameter, 3 mill. ; height, 1 mill. 



Fig. 43. 



Helix {Conulus) chcrsinella, Dall, Amer. Journ. Conch., II. 328, 



PI. XXI. Fig. 4 (1866). 

 Conulus chersiyiella, Tryon, Amer. Journ. Conch., III. 162 (1867). 

 Z. chersinellus. Hyalina chersinella, W. G. Binney, L. & Fr.-W. Sh., I. 47 (1869). 



" Big Trees," Calaveras County, California : it must be considered a species 

 of the California Region. 



The description and figure are drawn from an authentic specimen. 

 Animal not observed. 



Zonites capsella, Gould. 

 Vol. III. PI. XXIX a. Fig. 2. 



Shell quite small, planorboid, pellucid, glistening, amber- 

 colored ; spire nearly plane, composed of about 6^ closely 

 revolving, flattened whorls ; surface with distant, impressed, 

 radiating striae ; suture margined ; aperture narrow, semi- 

 lunar; peristome simple, not thickened by callus within; base 

 perforated by a deep, rather small, funnel-shaped umbilicus. 

 Greater diameter, 5 mill ; height, 2^ mill. 



Helix rotula, Gould. Pt'^.^^. Bost. Soa, III. 38 (June, 1848). — 



Pfeiffer, Mon. Hel., III. 107, preocc.i 

 Helix capsella, Gould in Terr. Moll., II. 239, PI. XXIX. a, 



Fig. 2. — W. G. Binney, Terr. Moll., IV. 117. — Lewis, Amer. Journ. Conch., 



VI. 188, ri. XII. p. 12 (1871). 



1 The strict rules of nomenclature would require the use of Gould's first name, rotula, 

 which is not preoccupied in Zonites. 



Z. capsella. 



