HELIX-THALASSOHELIX. 71 



in the center, runs along each side, and below the band the foot 

 is edged with alternate broad gray and narrow white tranverse 

 bands. (Hutt.) 



Auckland, Napier, Wellington, North Island; and Waipara, Wai- 

 taki, Queen stown, Dunedin, Lake Guyon, Waiau, Southland, South 

 Island, N. Z. 



Therasia thaisa HUTT., Trans. N. Z. Inst. xvi, p. 182, t. 9, f. M, 

 t. 11, f. T (jaw and dentition). Helix ophelia Rve., non Pfr. 



A common species in limestone districts of the South Island. 

 My figures were drawn by Mr. Suter from the type. 



G. DECIDUA Pfeiffer. PI. 22, figs. 52, 53, 54. 



Shell depressed, subglobose, thin and fragile, narrowly umbili- 

 cated. Surface having oblique striae and very fine, close spiral striae. 

 Brownish-horny, obscurely marked with brown, subtranslucent. 



Spire low-conoid, apex obtuse. Whorls 5, the last obtusely 

 angled above the middle. Aperture somewhat oblique, round- 

 lunate ; peristome thin, simple, expanded at the umbilicus. 



Alt. 6, diarn. 8 mill. 



Auckland; Wangaruru, N. Z. 



H. decidua Pfr., Monogr. iv, p. 71. Therasia decidua HUTT., 

 Trans. N. Z. Inst. xvi, p. 203. 



G. TRAVERSI E. A. Smith. (Vol. II, p. 214.) 



Allied to the last, but more distinctly marked with brown and 

 with more acute carina. 



Section THALASSOHELIX Pilsbry. 



Thalassohelix PILS., The Nautilus, Sept. 5, 1892, p. 56, type H. 

 zelandice. Thalassia of HUTTON and other New Zealand authors. 

 ?? Thalassia ALBERS, Die Hel. 1860, p. 59. Not Thalassia 

 Chevrolat, 1834, a genus of Coleoptera. 



It is somewhat doubtful whether the New Zealand species belong 

 to Thalassia of Albers, if we restrict that group to species similar 

 to its type, H. subrugata Pfr., of Australia. This species presents 

 certain conchological features which would cause me to separate it 

 from the following New Zealand forms, even if a change of the 

 name were not necessary on the ground of preoccupation. 



