GASTEROPODA. 93 



carinated. Seven-eighths of an inch in breadth. Inhabits dry 

 situations in Europe. 



Genus 81.— HELIX.— ZmHa>MS. 



Generic Character. — Shell orbicular, convex or conoid above ; 

 sometimes globular, with the spire somevi^hat elevated ; aperture 

 entire, transverse, very oblique, contiguous to the axis of the 

 shell; having the margin disunited by the projection of the 

 body. 



Helix arhustorum. — The Grove Helix. Plate XIII. fig. 

 27. Subglobular, subumbilicated, finely striated longitudinally ; 

 greenish-yellow, beautifully mottled, and streaked with reddish- 

 brown, and a broad brown band running throughout the middle 

 of the volutions. One inch in diameter. Inhabits the groves 

 and woods of Europe. 



ORDER IV.— GASTEROPODA. 



Animals with straight bodies, and never spiral, nor enveloped 

 entirely in a shell, having a foot or muscular disk under the ab- 

 domen, attached to the body nearly its whole length, and serving 

 for progressive motion. 



Section I — Pneumobranchije. 



Branchiae, constructed like a vascular net, on the wall of a 

 particular cavity, opening by a perforation which the animal has 

 the power of contracting and dilating at pleasure. They respire 

 air. 



TRIBE I. LIMACINEA. 



The animals almost wholly naked, with elongated bodies ; and 

 they creep by means of a ventral disk, with a narrow mantle 

 bordering their sides. 



