372 



TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Fig. 254. 



Helix Gabbii, Newcomb, Proc. Cal. Acad. Nat. Sci., III. 117 (1864). —W. G. 

 BiNNEY, L. & Fr.-W, Sh., I. 175, Figs. 304, 305 (1869). 



Aglaja Oabbii, Tkyon, Am. Jourii. Couch., II. 315, PI. VI. Fig. 



19 (1866) ; III. PI. XI. Fig. 31 (1867). 

 Helix facta, Newcomb, Proc. Cal. Acad. Nat. Sci., III. 118 (1864). 



— W. G. BiNNEY, 1. c, Fig. 306. 

 Aglaja facta, Tryon, Am. Journ. Conch., III. 162, PI. XI. Fig. 32 

 (1867). 



A. Gabbi. 



Fig. 255. 



A. 

 tenuistriala. 



Fig. 256. 



A. facta. 



San Clemente Island, California. 



Under the name of H. tenuistriala (certainly not of Binney) I 

 have received a shell from Catalina Island, apparently a less de- 

 veloped form of //. Gabbi. It is here figured. (Fig. 255.) 



Although I am convinced of the identity of facta with Gabbi, I 

 repeat below the description of the former, with a figure of an 

 authentic specimen. 



Shell imperforate or subperforate, globose or depressed-globose, 

 smooth, shining, surface hardly broken by delicate incremental 

 striae and revolving lines, light fawn-color above, below lighter, 

 with a median, white-margined, revolving band of a darker-col- 

 ored hue ; spire elevated, apex obtuse ; whorls 5 to 6, rather con- 

 vex, the last slightly descending, globose ; aperture oblique, banded 

 within ; peristome thickened, brownish, shining, its inner margin 

 rounded, reflected, the columellar portion dilated, appressed, par- 

 tially or entirely covering the umbilicus. Greater diameter 14, 

 lesser 1 2 mill. ; height, 8 mill. 



Santa Barbara Island, California. On this and San Nicholas 

 Island is found a larger, heavier, extinct variety. South end of Catalina Island. 

 The species has the stout, white, parchment-like epiphragm characteristic of 

 Arionta. 



Jaw arcuate, of equal breadth throughout; anterior surface with distant, 

 stout ribs, denticulating either margin. 



Lingual membrane long and narrow (PI. IX. Fig. P). Teeth 26 — 1 — 26, 

 as usual in Arionta. Morse counted 114 rows of 29 — 1 — 29. The fourth has 

 a decided side cusp and cutting point, which on the central and first three laterals 

 were replaced by a prominent bulging of the large cutting point. The thir- 

 teenth tooth has its inner cutting point bifid. My figures give the central with 

 the first, fourth, twelfth, thirteenth, seventeenth, and twenty-sixth teeth, the 

 last two being marginals. 



Genitalia (PI. XVII. Fig. 9 of Ann. Lye. Nat. Hist, of N. Y., Vol. XI.) 

 without the accessory duct of the genital bladder, and with a dart sac. They 

 resemble nearly those of ruficincta (see above), differing chiefly in the length of 

 the duct of the genital bladder. At the base of the dart sac there appear two 

 simple, thread-like organs, reminding me of those of Stearrisiana, but without 



