THE YOUNG NATURALIST. 



295 



CONCKOLGGY. 



By Mr. H. T. Robsox, Stockton-on-Tees. 



The Geneva of each family have all been 

 named, and it remains to describe them, and 

 to give the species contained in each with 

 such particulars of them as may be desirable. 



FAMILY, LIMACINEA. 

 Genus, Arion. 



This is the first genus of the Slugs, or 

 shell-less Mollusks, the mantle is represented 

 by what is termed the shield, which covers the 

 back of the animal near the head, they have 

 four tentacles, the eyes being placed at the 

 points of the two longest, there are two 

 species, Ate)' and Horfensis. 



Ater is the common black slug so fre- 

 quently seen in fields, gardens, and woods, a 

 familiar object to everyone. 



Hortensis is a smaller specie's, yellowish 

 or grey, with darker stripes down the back, 

 it may be met with in gardens. 



Genus, Geomalacus. 

 This genus contains only one species Macu- 

 losus, a rudimentary shell is enclosed within 

 the shield. 



Maculosus has only been found in the 

 West of Ireland, it is black, spotted with 

 yellow, and is said to be very pretty. 



Genus, Li max. 

 The principal feature which distinguishes 

 this genus from the two preceding is the 

 position of the opening through which they 

 breathe. Limax has it at the right margin 

 of the shield behind the centre, while in the 

 others it is more in front ; there are four 

 tentacles, the upper pair being the longer, 

 and bearing the eyes at their extremities. 

 Some of the species have a rudimentary shell. 

 The species are Sotverbyi, Gagates, Agrestis, 

 Marginatus, Brunneus, Tcnellus, Flatus, and 

 Cineveus. 



Sowerbyi-— This slug' is yellow, with 

 brown markings, and has a yellow ridge, or 

 heel, on the back, it is a garden slug found 



in the South of England. 



Gagates has also a keel on the back. Its 

 color is grey. It has only been found in a 

 few localities, 



Agrestis- — This little slug is flesh color, 

 mottled with grey. It is the well-known pest 

 of the garden. It is remarkably prolific, 

 abounds everywhere, and is very destructive 

 to vegetation. 



Marginatus.— Grey, with two dark lon- 

 gitudinal bands ; it is a tree slug. 



BmnneuS- — A brown slug. The smallest 

 of the genus. 



Tenellus. — A very rare species, pale 

 yellow. 



Flavus. — This is a large yellowish slug, 

 found about cellars, and in other similar 

 situations. 



Cinereus. — This is the largest species. 

 It is ash colored, with leopard-like markings. 

 It is a handsome sing, and may be found 

 about gardens and hedges, and sometimes 

 about cellars. 



Genus, Testaciila. 



This genus forms an intermediate link 

 between the slugs and the snails, having a 

 small external shell on the hinder part of the 

 back. It resembles a slug in general ap- 

 pearance, but is without the shield, the 

 mantle being towards the tail, beneath the 

 shell ; the breathing organ is also towards 

 the hinder part of the animal, the opening 

 being at the edge of the shell ; they are car- 

 nivorous, feeding on earth-worms and slugs. 

 There are two species, Haliotidea and Mangei, 



Haliotidea- — The animal is yellow, with 

 depressed markings, somewhat resembling 

 the veining of a leaf; the shell is small and 

 ear-shaped, and is covered by epidermis ; it 

 is formed by successive layers secreted by 

 the mantle in the usual way, a»d shews a 

 slightly spiral tendency. It is found in the 

 South of England and Ireland. 



Mangei- — This resembles the preceding, 

 but is darker in color, the shell larger, and 

 not so flat. 



