234 AMERICAN JOURNAL 



labris group than is Townsendiana, and probably extends far 

 into British Columbia, as it is not found southward, possibly 

 meeting with eastern species near lat. 55°. 



We also find here the type of an entirely new group (IT. 

 Jidelis,) beautifully colored and very large, inhabiting a region 

 of excessive winter rains, moderate summer heat and a short 

 dry season, and ending its range southward at the prominent 

 cape where the coast line bends to the southeast, and a general 

 change occurs in the climate, vegetation and animal life. The 

 other two larger species of the Oregon group also end their 

 range southward before reaching this point, and the two smaller 

 ones continue only in favorable situations close to the coast down 

 to lat. 37°, their companion Vancouverensis dwindling down to 

 half its northern size, if indeed it is not distinct. This, however, 

 like the Anguispirce, partakes of the spreading powers of the 

 smaller Helicellinrp, though in what way the spreading of those 

 large forms is effected, we cannot so easily see. It is really 

 scarcely more than a form of the eastern coneava at best. 



We now enter the Californian fauna and soon find an entirely 

 new group of species, excepting the three mentioned. Most of 

 trtiese are banded Yike Jidelis, but form two sub-groups of nearly 

 equal numbers, one with the smooth surface and fine revolving 

 impressed striae of Jidelis, the other with a wrinkled surface not 

 unlike that of Townscndiana (which, however, has the striae 

 also). The character of those two species are combined and mo- 

 dified into a great variety of forms. Strangest of all, the one 

 which seems nearest to Jidelis, and its geographical continuation 

 southward, (infumata) loses both its color and sculpture, becom- 

 ing black and hirsute, so that without the intermediate form it 

 would be considered very distinct. It is the analogue of strigosa, 

 and its changes seem connected with similar conditions of climate 

 and topography. But passing eastward into a warmer and drier 

 region, we find the Mormonum, which has lost the angular char- 

 acter, at least when mature, though retaining considerable flat- 



* It seems somewhat doubtful whether the Californian form is identical 

 with Vcuicouvere?isis, at least south of lat. 41°. Besides being only half 

 as large when adult, specimens of the same size differ as follows at San 

 Francisco and the Columbia river (Astoria). The former is more convex, 

 its whorls more rounded, surface much smoother and more shining, and 

 umbilicus more expanded. In all these characters it agrees with coneava, 

 though the umbilicus is perhaps less expanded and the colorless green, 

 being a paler yellow than that of the northern ones. Specimens from 

 Sitka, however, are still more swollen in the whorls, and of a very bright 

 yellowish green. The Astoria specimen of the same size has the same 

 number of whorls as ours, and also the same as those of double its S'ze, 

 viz — five. 



