MOLLUSCS. 311 



f 

 beerif, described. A concise definition of the group is impossible, yet all of its mem- 

 bers are readily recognized by the tyro as belonging to the family. There is an in- 

 Jescribable something which at once tells the student that the specimen before him 

 belongs to the family Helicidae. Still, notwithstanding the fact that we cannot frame 

 a satisfactory definition, it will be well to review a few of the characters found in the 

 group. 



In all, the upper jaw is present and opposable to the lingual ribbon ; the tentacles 

 which bear the eyes are longest and can be invaginated. The shell is spiral, usually 

 well developed, and capable of containing the whole animal ; the reproductive orifice 

 is near the base of the right ocular tentacle. An immense number of genera and sub- 

 genera have been made in order to render the identification and classification of the 

 numerous species an easier task. Even the family Ilelicidse has been broken up into 

 divisions, each of which have been accorded family rank, but which here are regarded 

 as sub-families. Space and the patience of our readers will allow but the mention of 

 but a few forms, while our illustrations will show the general appearance of many of 

 the species found in the United States, as well as a few from foreign countries. 



The Helicidse are all terrestrial, herbivorous animals, which delight in woods, es- 

 pecially in limestone regions. In Europe, some species have proved _ _ _ 

 themselves nuisances to the agriculturist, but with us they have not ^ ^l \ 

 yet done much damage. Our American forms seem to avoid culti- 

 vated places, and the little damage done the fai-mer or gardener by ^'"*- ^fii^^'"''^'"^ 

 the molluscs is occasioned by the slugs {Limax) and a few imported 

 snails. Why there should be this difference between the snails of Europe and America 

 is not easy to say ; possibly it is because our native species have not yet had time to 

 adapt themselves to the changed conditions which accompany civilization ; and they 

 still adhere to the traditions of their fathei-s. 



The land snails possess great vitality, and as an illustration we cannot refrain from 

 quoting the wonderful history of a specimen of Helix desertorum, which has figured 

 in man'y a work on the subject of the Mollusca. This specimen was brought from 

 Egypt to England. It " was fixed to a tablet in the British museum on the 25th of 

 March, 1846 ; and on the 7th of March, 1850, it was observed that he must have 

 come out of his shell in the interval (as the paper had been discolored, apparently in 

 his attempt to get away) ; but, finding escape impossible, had again retired, closing 

 his shell with the usual glistening film ; this led to his immersion in tepid water and 

 marvellous recovery." Even longer was the life of a specimen of Helix veatchii, from 

 Lower California, detailed by Dr. R. E. C. Stearns. This individual lived six years, 

 from 1859 to 1865, in confinement, without food. 



The time of oviposition is from April to June. The number of eggs varies from 

 thirty to fifty or more. They are laid in the light, moist mould, each one separate, or 

 united by the slightly adhesive exterior. There is no gelatinous matrix like that 

 found in the aquatic forms. In laying the eggs, the snail usually burrows its head into 

 the soil, stretching the body to the utmost extent. Since the reproductive orifice, as 

 has been said, is beneath the upper tentacles, this places the eggs at a distance beneath 

 the surface about equal to the length of the body in front of the shell. Other species 

 actually burrow beneath the surface to the depth of three or four inches before laying 

 their eggs, so as to insure a moist condition. 



It isrelated that the eggs possess great vitality, and that they are capable of with- 

 standing desiccation. When so dry that they had 'lost all form, and were reduced to 



