THE SLUGS. 



223 



rather gorges, upon worms. The feebleness of the shell-producing functions in the Limadd-ai is 

 largely compensated by the faculty of secreting mucus of a particularly viscid kind from all parts of 

 the body. The Slug will lower itself to the ground from a tree or shrub even from a shelf when 



brought into a room by the mare accumulation of mucus at the extremity of the tail hardening into 



a gelatinous thread. The animal functions are not suspended during hibernation and at other periods, 

 as in the Snail ; and the animal is at all times more tenacious of life. The continued secretion of 

 mucus is necessary to the Slug's existence. When this faculty ceases and the integuments dry, the 

 animal dies." (Reeve.) 



Genus Limax. Limax has the foot pointed behind and keeled throughout the back ; the mantle 

 is shield-shaped, and placed on the 

 anterior portion of the back ; the 

 breathing orifice is on the right 

 side, near the hinder margin of 

 the mantle. The creeping - disc 

 extends the whole length of the 

 animal, but they frequently lift 

 up their heads like the Snail, and j? 

 move their tentacles in search 

 of objects above them. When 

 alarmed, they withdraw the head SLUG. (ARION ATEK, " BLACK ARION.") 



beneath the mantle and contract 



the foot. In dry weather and in winter they bury themselves in the ground. Twenty-two species are 

 found living in Europe and the Canary Islands. 



Genus At'ion. The Slugs of this genus are distinguished from those of Limax proper by the pre- 

 sence of a pore or gland, for the more copious secretion of mucus, at the extremity of the tail, and in 

 h:i ving the pulmonary sac and overlapping shield nearer the head, with the respiratory orifice in front. 

 The shield has no internally developed shell, its place being occupied by merely a few calcareous 

 grains, which are sometimes isolated, sometimes aggregated into a rude irregular mass. The body 

 is enveloped by integuments of considerable density, rising into wrinkle-like tuberosities or leaflets, 

 and there is no dorsal keel. (Reeve.) They lay from seventy to one hundred eggs between May and 

 September, which are twenty to forty days in hatching, and attain their full growth in a year. Six 

 species are found in Europe and Africa. 



Genus Parmncflla.* The Parmacella has a large foot, pointed behind; the mantle is small 

 and shield-like in the middle of the back, partially concealing the small oblong and nearly flat shell, 



which has a sub-spiral apex. There are 

 seven species, found in South Europe, the 

 Canary Islands, and India. 



Genus Testacella. The shell in Testa- 

 cella is small and ear-shaped, and placed 

 at the hinder extremity of the body, which 

 is elongated, broadest behind, tapering 

 towards the small head. Testacella is 

 subterranean in its habits, feeding on 

 earthworms, and visiting the surface only at night. During the winter and dry weather 

 the Testacdht forms a sort of cocoon in the ground by the exudation of its mucus. If this cell is 

 broken the animal ina^ be seen completely shrouded in its thin opaque white mantle, which rapidly 

 contracts until it extends but a little way beyond the margin of the shell. Testacella has been 

 found in gardens in London, at Norwich, and in a field in Devizes. Three species are known in 

 the South of Europe, the Canary Islands, and Britain. 



FAMILY XXIA'. ONCIDIAD^E. 



The animal is without a shell, and completely covered by coriaceous mantle. 



Genus Oncidium.\ The characters of this genus are, animal tuberculated, oblong, convex, with 

 * Greek, panne, a shield. t From Greek, onkos, a tubercule. 



LINGUAL TEETH OF TESTACELLA HALIOTIDES. 

 (After a Drawing by S. P. Woodward.) 



