The “prevailing” snail of this region is _Cepolis ovumreguli_ Lea. Its shell is very suggestive of the true helix of Spain or Algeria of the _lactea_ group. The variation is exceedingly great in color, size and shape, and it would make a dozen excellent species if the intermediates were left out of account. Those living near the coast and among the cacti of the most arid parts of the district are of whiter and more dull color, are more banded and show a decided tendency to abnormalities, especially about the apertures. Specimens from further inland are more polished and shining, even as though varnished, and are much more given to a dotted or fly-specked type of ornamentation than to bands. A fence-post or a dead tree-limb with a hundred specimens closely assembled in aestivation was no unusual sight. We learned finally to pay no attention to them. Upon the low bushes in certain localities the lovely little _Cepolis lucipeta_ Poey cling like berries. These are the largest and finest of the species I have ever seen. The range of color variation in this delightful little snail is also very great, but the colors never blaze out in the vivid flash of the Polymitas. The blues and purples and chestnut browns are subdued but very rich and splendid. One very noticeable color form is the subsp. _velasqueziana_ of Poey where the many broken bands of the type coalesce into two broad bluish-black zones of solid color. As nearly all the vegetation of this dry region bears thorns we did not at first discover that many of these thorns were in reality Macrocerami. When we did find this out we could see nothing else. Bartsch and I finally agreed, and shook hands upon it, that we would gather no more of them, and a stiff penalty was placed upon any violation of the compact. Two hundred and more from one bush is an earlier record before we really got started. This is the _Macroceramus festus_ (Gundl.) Pfr., blue and yellow and buff in color. Another arboreal snail of this section is _Polymita versicolor_ Born and it is probably very abundant in places although we never saw more than fifteen or twenty on any one tree. This is to me the least attractive species of that wonderful genus of richly painted snails. The brilliant yellow and pink are too primitive and the two colors do not seem to harmonize very well. It always impresses me as an experimental species that was laid aside in nature’s laboratory as not wholly a success. There were some ground snails too, but to secure living ones required much grubbing up of tufts of tall grass and shaking out their roots, like digging up miniature potatoes. These are the _Annularia putris_ (Gundl.) Pfr. and the _Chondropoma marginalbum_ (Gundl.) Pfr., the latter apparently quite rare. There are no minute things beyond some few _Thysanophora inaguensis_ Weinland.