18 PROCEEDINGS OF THE CALIFORNIA 
and fossil, closely resembling West Indian forms, as well as some of the 
Canary and Azores Islands, he considers good evidence of the exist- 
ence of the connecting land ‘‘Atlantis’’ within tertiary periods at least. 
The cireum-tropical existence of this northern group is, however, to be ex- 
plained in another way by a southward migration, as I have more fully shown 
in another paper. The repetition of forms with very thick lips, in different 
longitudes, on islands between latitudes 35° and 30°, is rather the conse- 
quence of the excessive development of shell in mild foggy climates, on 
islands, especially, where lime abounds. The animals may differ very much, 
as shown by those with similar shells, from New Caledonia described by 
Crosse & Fischer. The Algerian fossils no doubt lived when the Sahara was 
an inland sea, and Algeria a group of islands, the later rise being possibly at 
the time ‘‘Atlantis ’’ sunk. 
Our fossil island varieties also show the effects of a former moister and 
warmer climate, perhaps pliocene. 
As might be expected, the Algerian shells belong to a different subgenus, 
forming a gradual series from the toothless Tachea lactea, Mull. (‘‘=lucorum 
L.,”’ Hanl.) to one and four-toothed Dentellarian forms, and some of, the fos- 
sils retain the characteristic five bands of the § Pentatenie. 
Our island Helices also connect with the Lower Californian many-banded 
areolata, etc., which much resemble lactea, etc., but according to Morch, 
Tachea is a subgenus of the carinated genus [berus (type Gualteriana L.) 
As partial evidence of the greater antiquity of our fossil forms, we may note 
that numerous eastern species found fossil in the Mississippi valley Quater- 
uary strata, do not differ from those now inhabiting the surrounding regions. 
In that case, therefore, there may have been no great change of climate. 
The angled form of Kellettii, found fossil, is the link connecting our ‘‘Ar- 
ionta-form’’ species with the ‘‘ Chilotrema-form”’ lapicida, and with the 
angled forms of the next group. 
Subgenus CAMPYLAA. (?) 
H. Mormonum Pe. In their splendid work on the Land Mollusca of 
Mexico, and also in the Journ. de Conchyl. XXI, 1873, 263, Messrs. Crosse & 
Fischer give as a locality, ‘‘Sonora, Mex., Dr. Frick.”” This is undoubtedly 
amistake arising from specimens collected by him at Sonora, Tuolumne 
County, Cal., where he informed me himself that he found it common, as 
well as at Columbia, near the same place, localities noted for the marble and 
lime mentioned by me in other articles. Lest other foreign authors may - 
suppose this shell to be from Utah, I may state that the original locality, 
‘‘ Mormon Island,” is a rocky islet in the American River, Cal., 70m. N. N. 
W. of the town of Sonora, and on the same Limestone belt.* 
The animal of H. Mormonum, (Pioneer Cave, El Dorado Co., J. G. C.), is 
long and slender, semi-cylindrical, foot not projecting much behind, flattened, 
*In the same works the anthors repeat the error of locality for H. Pandore, viz: ‘‘ Santa 
Barbara, Cal.,” though it has been several times exposed. They also redescribe Nassa fos- 
sata, Gld.. as ‘NV. Morleti, Crosse, Habitat unknown.” J. de C., 1868, 169, Pl. VI, f. 3. 
