LECTURES ON MOLLUSCA. 79 



like Helicella. The large tropical group of Nanina have the sole of 

 the foot broad. In some of the sections, the shell is rough above. In 

 Arioptranta, there are no mantle-flaps, but the slime-gland is still seen 

 behind the left-handed shell. Helicarion has a Vitrinoid shell, nearly 

 enveloped by the flaps of a Naninoid animal. The animal of Pary- 

 phanta is not known ; but the shells are like a large horny Vitrina. 



Family TESTACELLACID.E. (Carnivorous Snails.) 



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The great Glandina of South Carolina, and its congeners, have 

 the lingual teeth in curled rows and sharply hooked. The head is 

 short, and the lips are produced into false tentacles, as in the Ampul- 

 larias. The shell resembles a flattened AcJiatina. It is strictly car- 

 nivorous in its habits. 



A curious little group of slugs are found to have similar denti- 

 tion and habits. The teeth are pin-shaped. They are known from 

 the common slugs by not being slimy; living under ground, where 

 they prey upon earth worms; and having a little solid shell like a Sea- 

 ear on its tail. Its head however is shaped like the True Slugs. A 

 similar, but somewhat apocryphal slug is figured by Ferussae, with a 

 horny, conical shell on the tail ; it is provisionally called Plectrophorus. 



Family LiMAcnxffi. (Slugs.) 



The True Slugs have teeth very like Vitrina, but the points are 

 longer. The body of the animal is united to the foot, and a shield is 

 seen on the back, under which, in Limax, there is a calcareous plate, 

 which has been found fossil in the Eocene beds. They are pretty 

 active in damp weather, and love to feed on decaying animal and 

 vegetable matter. The Teneriffe Slug, Pkosphorax, has a bright 

 green spot on the tail, which shines at night like the glow-worm. In 

 the Philomycus of the southern States, the shield covers the whole 

 back of the Slug. 



The Arions, or Land-soles, have only a few granules instead of a 

 shelly plate, and have a slime-gland like Nanina. The common Eng- 

 lish species has 160 rows of teeth on its tongue, with 101 denticles in 

 each row. They freely eat dead worms; and, like true cannibals, will 

 not refuse to finish off an injured individual of their own species. The 

 Irish Slug, Geomalacus, has a shell like Limax, and a gland like 

 Arion. The reproductive orifice is under the right eye-stalk, as in 

 the True Slugs; in the Land-soles, it is just below the breathing 

 valve. 



A very curious New Zealand Slug, Janella, resembles Philomycus 

 in having the mantle produced over the whole back; but the eye- 

 stalks are behind the forehead, and the mouth beneath, at the front of 

 the foot-sole; so that the head is hardly distinct. The mantle is 

 grooved down the middle, and the breathing hole is half way down 

 the body. The creature coils itself round to sleep like a cat. 



Family ONCIDIAD^E. (Rough-Slugs.) 

 The Oncidia, like the Auriculus, live in damp places near the sea or 



