182 



A MANUAL OF AMERICAN LAND SHELLS. 



acute, its columellar extremity not reflected. Greater diameter, 2^™°^; 

 height ^™™. 



Helix exigua, Stimpson, Proc. Bost. Soc, iii, 175 (1850).— Gould, T. M.,iii, 16. — W. G. 



BiNNEY, T. M., iv, 102, pi. Ixxvii, fig. 19. — Pfeiffer, Mon, Hel. Viv., iii, 



102.— Mouse, Amer. Nat., i, 543, iig. 34 (1867). 

 Helix annulafa, Case, in Sill. Journ. [2], 1847, iii, 101, figs. 1-3; Ann. and Mag. Nat. 



Hist., 1847, 338, preocc* — Pfeiffer, Mod., iii, 103. 

 Helix striatella, junior, teste Gould, Sill. .Joiiru., iii, 276 (1847). 

 Pseudohyalina exiqua, Morse, Jonrn. Portl. Soc, i, 16, pi. ii, fig. 8; pi. vii, fig. 33 



(1864).— Tryon, Amer. Jonrn. Conch., ii,265, pi. iv, fig. 57 (1866). 



Hyalina exicjua, W. G. Binney, L. &. Fr.-W. Sh., i, 42 (1869).— Gould and BiNNEY, 



Invert, of Mass., ed. 2, 400 (1870). 

 Zonites exiguus, W. G. Binney, Terr. Moll., v, 122. 



A species of the Kortheru Region, noticed hitherto in Canada, New 

 York, and 'New England; Tawas Bay, Michigan. 

 Fig. 178 shows the peculiar sculpturing of this species. 

 Tig. 178. Jaw very low, wide, but slightly arcuate ; no median 



prominence to the cutting margin. 



The lingual membrane has G9 rows of 16-1-lC 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 



Surlace of 



z. exiguus. pass otf laterally. The transition teeth and several of 

 the adjoining marginals are described by Morse witli a small side spur 

 to their cusps, apparently of the same type as I have figured for 

 MacrocycUs Vancouver ensis (Terr. Moll., Y, Plate I, Fig. B). On Plate 

 III, Fig, D, I give a drawing of a specimen examined by me. I found 

 16-1-16 teeth, with 5 laterals. 



Fig. 179. 



Lingual dentition of Z. exiguus. (Morse.) 



*This name is preoccupied in Helix, not in Zonites, but cannot now be adopted ac- 

 cording to the strict laws of nomenclature, which recognize a long-established spe- 

 cific name. 



