316 



L WER IN VER TEBRA TES. 



The sub-family Achatininse embraces forms much like the HelicinEe but distinguished 

 by lingual dentition and by the fact that the lip is usually sharp, the columella trunca- 

 ted, the shell with an c4ongate spire, the body whorl being swollen. The genus AcJia- 

 tina, the agate shells, derives its name from the usually banded species. It embraces 

 the largest species of pulmonates known, e\en exceeding the genus Sulimus in this re- 

 spect, as some of the shells measure ten inches in length. The eggs are of proportion- 

 ate size and have a calcareous shell. Most of the species are found in Africa, where 

 they live in trees, descending to the ground to lay their eggs. 



In the genus AchatiiieH<i, the dextral or sinistral shell is much like that of Bulimus 

 in outline, but is distinguished among other characters by the spiral fold which accom- 

 panies the columella. The species are confined to the Hawaian Islands, but their num- 

 ber has been multiplied to an utterly unwari-anted extent, no less than three hundred 

 having been described. All are very prett}- shells, with a polished exterior, and striped 

 and spotted with bright colors, red, green, and brown predominating. We well know 



Fig. 37S. —Pupa 

 contracta. 



Fig. 379. — Pupa 

 armifera. 



Fig. 380. — Ptipa 

 pentodon. 



FiG. SSI. — Pupa 

 badia. 



¥m. 362.— Pupa 

 fallow. 



how inconstant is the number of bands in the land shells of the United States, where 

 the same species may be plain or ornamented with one or several spiral bands, but 

 these AchatiJiellw have been divided up mostly on similar characters. They live 

 largely on the low shrubbery near the sea, but since the introduction of cattle on the 

 islands thoy lia\'e become much less coTnmon than formerly, on account of tlie destruc- 

 tion of their food plants ; and their ultimate extinction is but a question of time. 



In the PuPiD^, we have a large number of generally small, many whorled, more or 

 less cylindrical shells, in which the a[.erture is frequently contracted by tooth-like 

 processes, like those previously described in some of the Helices. Our American 

 species of Pi<pa are almost all very minute, so that it requires good eyes to collect 



Fig. 383. — Fertij/o 

 ovata. 



Fig. 384. — Vertigo 

 milium. 



Fig . 385. — Vertigo 

 bollesianus. 



FiO. 3Se. — Vertigo 

 veniricosa. 



Fig. 3«1.— Vertigo 

 simplex. 



them. They seem to be even more dependent on moisture than most other land 

 shells. The species are largely based on the number and form of the teeth of the aper- 

 ture, the variations in which may be seen in our figures of some of the more common 

 species from the United States. One of the most important distinctions between 

 Vertigo and Pupa lies in the fact that in the latter genus the cephalic tentacles are 

 present, though small, while in the former they are absent. 



The genus Clausilia occurs in the regions surrounding the Mediterranean, its 



