206 AMERICAN JOURNAL 



shell. The larger size and possession of one to two more whorls 

 make it, however, somewhat doubtful, as we find the number 

 usually very constant in dwarfs of other species. The type is 

 much more globose than the form of Traskii {?) just mentioned. 



L. 3Iormonum^ Pf. The bristle-marks seen on the first whorls 

 in young specimens of this shell are not always perceptible, even 

 in those living, I have, however, found some with both these 

 and fine revolving grooves as in most others of § A. It con- 

 nects this with § B, not only by the bristles but by the angled 

 form of many specimens, running into L. Hillehrandi, L. infu- 

 mata, Gld. The angled and black specimens oi fidelis found at 

 Humboldt Bay are probably hybrids with this, as Mr. Gabb has 

 found it there. (Vol. IV, p. 224, note.) 



L. ? Roivellii, Newc. I have removed this from Group XII, 

 placing it doubtfully in § B, as the type showed only faint marks 

 of bristles which were possibly erosions, and Mr. Gabb in Vol. 

 IV, p. 235, contradicts his statement made in Vol. Ill, p. 236, 

 that the shell of Lohrii shows " minute punctations, as if the 

 live shell were hirsute," because he has since " seen fresh speci- 

 mens." Yet both statements may be correct, as in L. monno- 

 num the bristle-marks are visible only in very young or quite 

 unworn shells. L. ? Lohrii may be the peninsular representative 

 of Roivellii, which was more probably from Sonora, Mex., than 

 "Arizona," thus removing both from the proper Californian list. 

 They seem to be the subcarinate allies of the forms of Remondii, 

 found living with or near them, although varying from the simi- 

 lar instances observed in § B, a, in relation with § A, a, b. 



ARIONTA, Leach. 



A. arrosa, Gld. The var. /9. of W. G. Binney (Proc. Philad. 

 Acad. N. S., Oct., 1857,) is only a dwarfed form, common on 

 the cold treeless peninsula of San Francisco, and still smaller in 

 dry localities in Napa Co., having the typical seven whorls but 

 proportionally more elevated. The form mentioned by me in a 

 foot note to the " West Coast Helicoids," as resembling Pomatia 

 in form, and in this Journal, vol. IV, p. 222, as approaching 

 tudiculata, deserves more special mention. 



It appears to be the form figured by Valenciennes and copied 

 by W. G. Binney, as Helix arboretoj^um, which has usually been 

 considered a var. of Nickliniana. The figure is brownish-yellow, 

 dotted as if malleate or indented, and seems umbilicate ; band 

 single, diam. 1*05, axis 0-68, alt. 0*92, (I give both the axis of 

 the spire, and the altitude of apex above the general plane of 

 the base, as these differ in many species, and it is often difiicult 



